I knew of a family-run hoagie shop that sold to "investors" (not sure if it was PE, probably was) three times, each time they ran it to shit amazingly quickly, and they were able to buy it back for a song and fix the damage.

This is surprisingly common. I know a few people that recycle their businesses through PE, getting a payout each time.

The trick is that the business owner has a good relationship with his customers. After the PE investors run it into the ground, they can credibly reach out to customers directly, assure them that the adults are back in charge, and basically be a hero to the old customers who hate what the business became.

Yep! These situations are annoying for the customers, but an amazing opportunity for people trying to run good businesses. Let the bad operators run a company into the ground and then buy the pieces at an amazing discount.