I'm riding herd on quote a lot of sites so I get link request emails all the time. A lot of them are of course, automated garbage (the best ones are the guys who forget to take out [insert your website here] from the template). More and more I've been getting requests for three way links that are essentially useless. The site they're asking for a link to is usually pretty okay, sometimes pretty good. I would trade with them if the neighbourhood was right. The site I would actually get a link from is always garbage. Usually an over-linked PR0 directory full of pornography, dating, MLM, etc. Sometimes you can just go to the directory site itself and get a free link anyway (as if you'd want to). Usually it's completely unrelated thematically to the first site, and often my own site(s). In one memorable instance the linking site was actually on the StopBadware/Google Malware block list. Do people fall for this stuff? If you get an offer for a three way link do you at least check who the other two parties are? Also, have any of you ever gotten a real 3-way link request that wasn't just a bait and switch scam of getting a good link out of you for a bad link out of them?
I've never received one, though I don't doubt that they happen all the time. I've received plenty of link requests where the person requested a link on my directory (which doesn't have that many links...on a relative scale). and the link back to my site? 9 times out of 10 it's on some link farm, some overcrowded directory, etc.