Here is a portion of the Washington Post article I posted earlier which says a lot. That entire article is very fair to both sides of this issue:
"When you stiff waiters for bad service, you might be penalizing them for something that’s not their fault, such as a backed-up kitchen. And you might be stiffing the rest of the staff, too: Many restaurants pool tips, and servers give a share of their tips to busboys and bartenders, and sometimes even the dishwasher and hosts. At corporate restaurants that electronically track and report tips for tax purposes, employees may be taxed on the full amount of the night’s tips, even though they have to distribute a portion of them to other staff members. Some restaurants also take
credit card transaction fees out of their employees’ tips"