Does Amazon enable comment spam?

Comment spam has been around for many years now and I've seen all the tricks of the trade blasted at me and my sites. Lately, it's gotten tougher and tougher to weed out every last bit of spam because it's clear comment spammers are hiring people to write somewhat on-topic comments and then loading either their username or the comment with links to their sites (which are loaded with ads).

Here's an example of what I'd call a high quality comment spam:

It's on topic, it seems like an innocuous pat on the back in broken english, but the username links to a video game fan site. The comment was posted to get a backlink to their site. Sometimes they copy and paste two sentences from my own post as a new comment, but usually it's a mellow "this is a good post" comment meant to fall under my radar and eventually improve their Google ranking for whatever keyword they are chasing.

I started thinking about how people are farming out this "make an innocuous comment and link back to my site" work and I was reminded of Amazon's Mechanical Turk system where you pay humans to perform piecemeal work, often for mere pennies. A couple years ago, ReadWriteWeb noticed somewhat spammy activity on the Turk system so I decided to run the same searches today and found similar results.

• 29 results for "bookmark" including people asking for comments on their site and posting their site to every social bookmark system, some paying as little as a penny per job.
• 42 results for "comment" including lots of rate and comment my youtube videos up, test our comment system, and flat out "leave a good comment on my site" jobs.
• 18 results for "digg" including people asking digg votes as well as posting their site to digg for them.
• 13 results for "write a paragraph" These frequently become posts on adsense-loaded sites and other SEO nonsense.

I'm sure there are bigger sites that enable these kind of bottom-feeder transactions on the web. I bet there are whole black hat SEO forums and marketplaces to buy links, comments, and articles, but it's kind of a shame that two years after ReadWriteWeb pointed out the problems they still persist. I love using Amazon as a customer and I think the Mechanical Turk system is pretty cool, I just wish they did a better job eradicating this kind of thing that leads me to have to judge all my incoming comments harshly as defaulting to spam unless they seem like honest additions to the conversation.