My husband rarely does work on the side anymore as he has no time, but he sometimes found the opposite to be true. Errors on the side of thinking they could write off just about anything, even though they weren't supposed to.
We had one friend who used my husband and when he looked at their prior several years' returns he couldn't believe what that CPA had signed off on.
He did their taxes but said he would NOT sign off on something they wanted but couldn't have. He is a rule follower and wants to keep his license.
They never used him again.