Pete, I sometimes buy pre-made graphics from multiple companies such as Image Works, Lethal Threat, Universal Products, and auto trim express. Back about 4-5 years ago some of these companies started doing graphics on vinyl with air brushed painted designs on them. When applying them with paper backing you could stretch the graphic a good deal and cause the print to look bad. So, they switched to the plastic stuff. This eliminated the problem except for 2 new problems. 1, was that you had to use the graphic relatively soon after the pre mask was applied. 2, if the pre mask was applied too quickly after the decal was made it could cause the print to come off when peeling the pre mask off. Now, many of these companies are making decals with much higher degree of detail and such so they have to know what to do. It's crazy when you pull the decal out of the box and start to apply it you can smell fresh paint !!!!
My issues were with the fender and rear spoiler "trans am" names. Mind you, I installed the whole entire kit at the same time and same techniques. No where else did I have any issues. When I got to these parts, the pre mask looked old and a little bit yellowed. Only reasons for this is that they either were on the shelf for a long time or were exposed to high temps for a time (it was 93 degrees out when I got them so who knows how hot they got in the FedEx truck). Luckily for me knowing what to do, I was able to correct it. Others I am sure aren't. I can't see that it's "installer error" all the time when you can get simular products from other vinyl graphic companies, even those that make the same exact kits for our F-Body'd cars
Here's some links to the other companies that I use.
http://www.lethalthreat.com/products/vehicle-graphics/http://www.autotrimdesign.net/4x4_Decal_Kits.asphttp://www.imageworksmedia.com/digital_auto_graphics.shtml