Just a thought! I am seeing a lot of sites turning up in the supplimental results of Google. When you are considering a link trade it is very important that you check for this. When a page goes into supplimental it may mean 8-10 months before Google looks at the page again. That means that your link may show on the page but google doesn't know about it because they never check the page again. Use "Site:" to see if the page is in the main index, if it shows as a supplimental don't bother with the trade. Also worth checking the pages cashe to see if a page is getting reindexed regularly.
I'm going to have to disagree that it take 8-10 months for google to look at a page in the supplemental, as I've had pages removed from it in under a week, but you make a good point about checking if a link sucks or not.
I've had pages in sups for over 8 months before I noticed and did something about it. YES, it can definatly take over 8 months for them to check again. By fixing the problem and adding links to the pages you can get it out again quickly, however the person you are trading links with may not know he is there so he may not ever do anything about it.