Has anyone else who's searching in HVAC/home services come across business owners that take large amounts of cash payments for services? Does that affect your decision to acquire them?

How do you weigh the amount of cash income in the valuation and offer on the company?

Its not unusual that many home service businesses take cash and the books don't reflect that and some of the information that these owners are saying about taxes, cash and paying people off the books is a liability. Has anyone acquired a service company that was paying people off the books and then acquired it and put people on payroll?