Questionable management companies

[Tom I.]

Hey Biggerpocket friends,

I am starting to look for a reputable property management company in the metro Detroit area, seeing that I am new to multi unit rentals.

My concern is that my go-to heating and cooling guy warned me about a very large property management company in the area that he does work for. Apparently this company adds a 20% charge on whatever invoice he writes and makes the landlord foot the bill. The management company advises this contractor to not provide a price to any landlords/owners.

Is this something that is common? Are there any practices you put in place to avoid such shady companies?