Since I've done both, boarded and now keep my horses at home, I know what it takes to keep them happy and healthy. I also know that in a boarding situation, you are not going to get the kind of attention for your horse that you give him at home. It's not their horse, no reason why they should give him that kind of attention. As long as the stalls are picked 2X/day (a lot more often in a show barn) and they're fed on time, and NEVER allowed to run out of water, you're getting pretty much what you're paying for. Letting the horse run out of water is a deal breaker for me and I've fired barn help for that. ONE time and you're gone, so I would move from a boarding facility that let my horse run out of water or if I found the water or waterer consistently dirty.
I will compromise a little on that, I have a trainer who is an old cowboy and he just doesn't see the need to clean water tubs. I want my horses water clean enough for ME to drink it. He's an awesome trainer, great with my horse and my horse worships the ground he walks on AND he's beyond reasonable in price. I take a jug of bleach and a brush with me and clean my horse's water barrel once a week.
Does he give my horse the kind of attention I do, no, but he figures that's my job and he's right. The horse is well fed and when he's trained, he's TRAINED, I never have to worry about holes in his training, ever. So, it's worth a little "give" on my part. Pick your battles carefully.