In mid-February, Google seems to have made an example of popular UK flower retailer Interflora by apparently penalizing it for questionable search engine optimization (SEO) practices.
Interflora stopped ranking for its key terms, such as "flowers," "flower delivery," and "Interflora".
After brushing up its act, Interflora regained pride of place for most of its rankings this past Sunday. (Details on Search Engine Land.)
Could a similar event happen to a travel site soon?
On bad days, it can seem as if the Google cops are off eating donuts, while a handful of travel companies engage in dark hat practices with impunity.
To be fair, in late September 2012, Google did a clean-up with its Exact Match Domain update, which resulted in more relevant travel websites being returned higher for longer tail terms.
Google is clamping down further by the day, such as yesterday when it may have penalized Russian link network SAPE.
We asked Danny Sullivan, founding editor of Search Engine Land and Marketing Land for his thoughts. Sullivan is, in our minds, the most knowledgable, impartial expert on the topic. He told us by email:

Google has stepped up its efforts intensely over the past two years, as anyone hit by the "Panda", "Penguin", or dozens of other recent updates well know.
I've no doubt people in the travel space are doing things they think are perhaps risky, know are risky or which are purely for search engine benefits, rather than for their users.
The closer they stay to doing what makes sense for their users, the more likely they'll escape any Google policing—which really does come, and often seemingly out-of-the-blue to some.
SEO: From naughty to downright policy-violating
Questionable SEO practices certainly range along a spectrum.
First, there's merely sloppy and amateurish work, which may or not be intentionally evil, like hiring bloggers to post link-back widgets only if the bloggers have a certain Google PageRank.
Then there's a middle ground of shadiness, with concerted attempts to manipulate rankings using practices that are in an ethical gray zone.
The truly evil stuff, of course, is the outright deceitful effort to dupe search engines by boldly violating Google's and Bing's policies.
The Interflora case shows that Google is willing to make a case and take action when faced with that latter circumstance.
Roll call of non-best practices
Without calling out specific companies, we've rounded up some general practices that struck Tnooz as questionable.
We asked Sullivan some drive-by commentary. While Sullivan is definitely not in the business of investigating shady practices, he had some overall commentary that we found insightful.
Duplicate content
Imagine there's a booking site called AnonymousTravel and that it has a number of pages focused on different selection criteria for, say, Munich. They specifically build pages for: Weekends (Wochenende), Breakfast (Frühstück), etc.
All of these pages return the same result set of lodging options, but are unique for search engines to rank for their long tail keywords. Only difference between these pages are:
- URL
- Page title
Sullivan's view:

Is that bad? Not necessarily, even if the same bookings are listed multiple places.
It would be better if there was more unique content, definitely.
And without that, the pages probably shouldn't rank well given that Google has its own duplicate content detection filters, which are trying to understand if there are several pages that are similar to each other and return only one of them.
Certainly shoving some text at the bottom just to say "weekend" a couple of times feels amateurish and not the type of quality that I'd expect Google or Bing to reward.
Internal linking
Let's say AnonymousTravel has a Dutch site whose pages internally link to a number of other pages for results in other global cities, which might strike some users as irrelevant.
For instance, if you're a traveler searching AnonymousTravel for an hotel booking in New York City, but you notice that a page with Manhattan hotel room results includes links to lodging in Utrecht, which is in The Netherlands.
Is that an attempt to manipulate SEO rankings, rather than help usability? Unclear.
Sullivan's take:

The internal linking isn't necessarily bad.
If you're searching for apartments in New York, but you're on a Dutch site with other apartments in other places, the site might have good reasons to want to let you know about those listings, beyond just the SEO benefit.
Yet Google also doesn't have rules that really try to control what you can link to within your own site.
Linking to partner business irrelevant to travel
Imagine a site called AwesomeBrilliantTropicalHoliday.com, a by-all-accounts upstanding website for booking a private reef house off the coast of Costa Rica.
Say this imaginary site has a page with a list of link partners that are in some interesting businesses, not at all them relevant to travel, such as Link Exchange Management, Engagement Rings, and Surge Protectors.
With some creativity, you can imagine you would need a surge protector or an engagement ring for your travel. But a link exchange management company?
In the absence of any other information, such as if the links are paid for or if the travel site is legitimate, is the practice of link exchange automatically suspect?
In other words, is participating in a link exchange on the face of it deserving of a second look as a potential backlink investigation because it might be violation of the Google Webmaster quality guidelines?
Says Sullivan:

A lot of this stuff is open-ended, and I don't have the time to be trying to investigate sites from scratch.
I will say "a linking page" isn't uncommon.
It's perfectly fine to link to other sites, even those not directly related to you, and it's often the case that people still want to exchange these.
But those types of pages and links have tended to degrade in value over time.
[A company] may have reason for wanting to link to [an external site], perhaps as part of a link exchange. That's not necessarily wrong by Google's standards.
[A linking page] is hardly a stellar page for users, though.
Thanks to shady SEO, there are some travel websites building pages just for SEO, where lots of garbage still ranks in results like crazy.
Case in point: larding your site with unnecessary content, such as by keyword stuffing in anchor text (in other words, 89 times inserting the word "rentals" in those links at the footer of a webpage).
This is a very old SEO technique, but it still works! A couple of trade SEO professionals we spoke with anonymously say they still encounter this practice by players across the world.
In case it's not clear what we're talking about, imagine a site called AnonymousTravel. Say that this site has a large amount of footer text at the bottom of the page, which does not really help any user, and appears to be merely written for search engines, to jack up the relevance of a page.
That's not ideal for anyone, but it might possibly manipulate search rankings. Google is watching, though. A major travel site might be shamed soon.
Closing thoughts on SEO
We'll leave the last word with Sullivan:

The issue is really back to the search results.
When you search for something, what do you get? Is it quality?
If it's not -- or perhaps even if it is -- why is it showing up?
If it's showing up for tactics clearly violating Google's or Bing's guidelines, that's the issue.
NB: SEO illustration is licensed under Creative Commons and created by Sean MacEntee