Now back to the OP — I know exactly what you mean. Invariably, every single batch of hatchery chicks I’ve gotten had a couple that battled pasty butt. Not one broody raised chick I’ve had suffered with a pasty butt. Not ONE!
I love to sit up in the run and watch my broodies bring the chicks off the nest. As soon as her feet hit the ground, it’s game on for the newly hatched babies! They find themselves constantly being hammered with flying dirt and shavings and bark pieces and little rocks and even the ever-scratching feet of an activity deprived broody! They squeal (or whatever sound a little chick makes when getting hurt) and run away, only to run right back for more at the next “Tuk-Tul-Tuk” from the broody. BYW, after all my observations of my broodies with their chicks, I have pretty much perfected the very distinctive Tuk-Tuk-Tuk all broodies use to call their chicks over for the “good eats” they find for their babies. It has a very harsh tone and inflection, but my bator babies respond to it just like the broodies’ chicks. It’s quite amazing.
I use a heat plate in my brooder (I cant say enough good about them). I no longer subscribe to the much used 95-90-85-80... degrees to use for chicks in a brooder. Mine spend most of their time during the day out from under the heat. And this is in a house that stays between temps of 68 winter/71 summer.
I also sift through the “stuff” in my chicken run to retrieve a dirt/sand mixture for the chicks. Initially I don’t let the little chicks have access to anything “extra” until I’m positive they know what real food is though. But it doesn’t take them long. Also, I do not use medicated feed. My newly hatched chicks eat the same feed as the rest of my mixed flock, an All Flock feed. I do have Corid on hand just in case. I’ve used it once, in the beginning, because I wasn’t sure. Better safe than sorry!
There was one last thing I wanted to mention, but CRS has just hit. I might or might remember, but if I do I’ll post it later. 
ETA: I just remembered! My bator chicks seem to grow bigger, faster than the broody chicks. I can only think it’s because they fill themselves with mostly a balanced feed versus all the “extras” a broody chick consumes.