After seeing this thread, I've been thinking all morning about which toys I've found disappointing. The problem is so far I can't think of any toys that have really disappointed me.
The Banprestos were crap, but according to the rules of this thread they don't count and I never really had high expectations for them anyway.
I guess the problem is that I do a lot of research before I buy a toy, so I generally know what I'm buying and also I really only collect Macross toys and Gundam Sentinel FIX toys. That's it two toy line only. I'll probably also buy the MPC Alpha/Legioss when they come out, unless they turn out to be total peices of junk.
As a kid, I collected Star Wars figures, but it's been what 20 years since I last bought one.
I guess I'm going to have to vote for the Yamato 1/72 scale YF-21 FAST Pack version as the most disappointing toy. Horrible color, poorly sculpted gunpods and FAST packs and the damn thing never wouldn't lock together properly in fighter mode.
Graham