How is it a bad trade if it's for a figure you want? It's subjective to the trader in question. I've gotten away with some trades that almost felt like cheating the person I was trading, but they agreed to it. I've also traded more for a figure I really wanted.
I traded an M&M Storm and an extra AA Metron for Crisis Green Lantern, Crisis Green Arrow, and Crisis Supergirl. At the time, Crisis was as hard to find as Hammer of Thor is now, and that Storm's interest level to me wasn't as much as Supergirl's for the Legion of Superheroes theme. So I made an objectively poor trade in hindsight, but I liked the figures I got at the time and utilized them until lately when they re-released them in DC 75th and Superman sets. And now they're even re-making Storm. So la-dee-freaking-da.
Actually nevermind... I traded around 20 pieces (two of which where chases) the rest were super rares and LEs for gsx magneto before he jumped to 90 dollars. That's why I treasure my mags and will probably never trade him because to me his value is worth far more than anyone will trade for him.
My biggest trade regret is the one time I got scammed on here (along with a group of other folks). It could have been worse, and the person hit some of the others much worse than me, but I did lose an HoT Cap and a few other $$$ figures.
I also used to make quite a lot of off-balance trades to a friend of mine, just to keep him playing. I'd trade SRs for old Uniques and stuff, because he would complain so hard about the power creep in each new set and say he could no longer compete with me and thus was going to quit playing (It's worth noting that he actually had much more disposable income than I ever have and could have afforded all the new figures himself, he just didn't view Heroclix as a priority purchase and spent all his cash on videogames.). I eventually got sick of his constant negativity and stopped talking to him - deciding that a smaller Heroclix group was better than a larger, whinier one - and now I regret many of those desperate trades.
Beyond that I'm usually pretty pleased with my trades. Sometimes I've made trades that were balanced at the time yet would be dumb NOW (I traded GSX Phoenix for HoT Volstagg, and had to throw in some sweeteners to make it an even trade; now the prices of those two figures have reversed), but I generally am pleased with the turnout, and generally find that people who trade on the 'Realms are pretty fair about things.
Could we maybe please get a Negative Man figure, if it isn't too much trouble?