I don't really mind tipping if it's the norm, and i've received good service. But on some websites they say to tip 25% if the service is exemplary, 20% if it is good, 15% if it is just ok, and only 10% if it is bad service...
10% if it is bad service!? That's what we pay here if it's good! They should get nothing if they give bad service, and to fuck with them if they are on minimum wage. They shouldn't be on a wage at all if they can't do their job.