Attitude, how it sits and looks overall is a big one for me. For example, like a NASCAR or road racer that sits higher in the front than in the back, and the track is so wide in the front that the tires stick out, yet the rear looks almost like it was tubbed. The theres the 49 Merc 4x4 look, or the rods that have shorter tires in the rear. OK, they mnight be wider, but look at the darn profile of the model and yuck. Wheels that have been twisted off the sprue so there is either a huge nub left on the rim, or a piece is broken out. Tires that come nowwhere close to having the bead sit on the rim. And finally, panel gaps. I see so many many times where someone takes the time to open doors, and then after the model is done the character lines dont match up, the doors sag, or have gaps so big yu could fit a hand thru them. OK, whew! Im done now