I've heard from a few people that as far as sprayer guys go, that the maaco type guys are some of the best due to practice/volume. You'll get out what you put into the prep. i'm guessing you just do all the prep, drive there early, rub it down with an oil and wax remover, then mask right before rolling it in to the shop...
You definitely have to mask it yourself in their parking lot if you take it to Maaco or Diamond or one of the cheap places
They will NOT spend more than three minutes on the tape
The maaco in Columbus Ga did a great job on my 70 trans am
But the only thing to mask was the back bumper and door handles and windows
And later I painted a door and fender on a 78 formula firebird
At night
In an open shop
And the breaker for the air compressor kept tripping
Got some mosquitoes in the paint
But the worst part was that right before we sprayed it we wiped the fender and door with paint thinner
And then somehow laid that rag on the roof
So the next day when we came back and moved the rag the paint on the roof was all lifted