I think with me being new to the hobby, trades are a great way to deal games. I haven't played everything yet, so if I come across a trade deal that is fair, I will most certainly do it as only one of my games is a true lifetime keeper. Space is not an issue for me, and I do not feel comfortable spending lots of money on games yet until I am much more experienced with conditions, prices, and being able to work on my games.
I would never post a for Trade ad for one specific game though. That seems like a deal that rarely gets done and needs lots of luck. I will totally just offer up a game for trade though, then if someone offers me a game, I will make my decision then. Since I really do not know what games will be forever games for me yet, trading offers me an avenue of getting different games in my home right away to see if they stand the test of time.