There are good dealers and bad dealers and it makes no difference what brand they are selling. Obviously some BRANDS have a lot more for a dealer to do than others but dealers are individual businesses and you will find the entire range of service levels and skills. I certainly wouldn't generalize that "dealers" perform poor service work (or good service work).
One CLUE I've always found to be helpful is whether a particular dealer will perform warranty work on units they did not sell. If they won't do this they are PROBABLY not a very good repair facility because there is fairly good money is performing this work but manufacturers will only pay for it ONCE. If they frequently have to redo work it's on their dime, thus they don't want any more warranty work than they have to take.
Good luck / Skip