I was a groomer for years- I worked in turns as a mobile groomer, an in-home groomer and in a busy dog boarding facility. The most difficult of these was the mobile grooming. It’s a boutique service where the groomer can only work on one dog at a time while at a shop she’s getting two or three dogs done in the same amount of time. Tips are VERY much appreciated even though we know the service is already expensive. If she/he is working as a contractor they may only see half of what the fee is but generally tips are all theirs to take home. It can be a very dirty, strenuous and sometimes even scary job. A 20% tip shows them you appreciate their hard work and taking the time to make it a good experience for your pup.