I worked in Maaco's for several years. If you're lucky enough to find one with a sterling reputation, then I say go ahead. Most are not quality orientated. The paintline tech, sanders, maskers, and detailers are usually paid little better than minimum wage, and are rarely worth that. The painter is usually well experienced, but they don't have time to check the prep work before painting, they're expected to be able to paint a car in under 1 hour, from the time it goes into the booth, until it goes into the oven. The ovens do nothing to harden the paint, by the way, they're just supposed to flash dry the paint so the detailer can work around the car within an hour of it's being painted. Everything is done at minimum expense to the shop. Paint is usually the cheapest swill they can buy, although some shops may offer higher quality materials, at added expense. Many shops still use synthetic enamel, which can lose up to 1/2 of it's gloss in under a year. Often, hardeners for the paint are cut back because they're expensive. Sandpaper and masking materials are the cheapest they can find. Bodymen are usually old hack artists who can't get work elsehwere, or kids straight from tech school. You get what you pay for...
Bob