@freemo i tip 0% by default. I've rarely experienced service I thought was tip worthy. in every place that offers tipping, the staff are doing the minimum effort required by their job description.
the one exception I can think off was unusually professional service offered by one energetic employee at a Taco Bell of all places. i actually took time out of my day to email the company praising the young man.
i think tipping be banned altogether. tipped employees should be paid like everyone else. if you wanna slip an employee some extra cash under the table because they could use it or they are going above an beyond, be my guest, but it should not be institutionalized. keep it under the table.