On the other hand, I've gotten just about every Testors spray color to perform well, at one time or another. Mike, I've gotten very good results with Testors Dark Sea Blue, several times now - the most recent of which you can judge for yourself: on my my PB4Y-2 Privateer chop job. Likewise, I got an essentially perfect finish from Dark Sea Blue rattlecans on a Blue Angels SkyHawk, for many years the pride of my desktop. When finally its paint did develop a problem, it was the Testors GlossCote (or whatever it was called) that started first to yellow, then to crack. You may be seeing this model soon, as I'm thinking of refurbishing it - this time without the Testors gloss coat, of course.
Two Testors colors I've found more problematic than the others are also two of the lightest: Flat Camouflage Gray and Flat White. Both go on very thick, are especially prone to clogging the nozzles and often suffer what I would call "micro-tarballing" - where, instead of fine droplets the can throws tiny, sticky globs, which don't lay down into a smooth finish but instead build up into something resembling a layer of gravel over everything. The effect is particularly heavy (i.e., obnoxious) on delicate PE, which ends up looking like it's covered with rime ice - or shotcrete. (A good effect - if that's what you're looking for! )
I'm thinking the above problem must have something to do with their white/lightest pigments, interacting with the flat finish - which could explain the rotten experience with your Flat Light Gull Gray, Donny. I don't remember ever using that particular color - but I have gotten decent results with their "regular" Flat Gull Gray. In fact, its far better performance than from my Camouflage Gray rattlecans was a major reason I switched my Boxer build from the latter to this color. Anyway, I just bought two more cans of it - knock wood...