Well, i've had good luck as far as those went..
Just starting out, playing with some little decals for myself and friends, i was using masking tape as I hadn't gotten transfer tape in yet. I found that the strong adhesive caused small "pickling" after i peeled the tape back, most bubbles around 1/8" or smaller.. I was worried, but after a day or two, they seemed to settle down. I thought it just might be the heat of the Florida sun as i'd applied them to my car, but after putting a couple large decals on a friend's laptop, they also "settled" after a few days and were perfectly flat.
I can only assume that has something to do with the porus nature of the vinyl.. in both cases they were Oracal 751.
Since then i've gotten proper transfer tape, and haven't had those issues since!