20% for good service, 10-15 for below average. I don't usually take the quality of the food out on the server, unless it's something they should have spotted before bringing it to my table. For example, if I order onion rings with my sandwich and I get french fries, the server should have checked the order against the ticket and spotted it.
If the service stinks, I leave about 5%. Not tipping is not nearly as effective in getting their attention as half a tip, as I've been told by people who work in food service. I can appreciate a server who has been on his or her feet for several hours before I get there and still can smile and be pleasant and does a good job serving me. The girls at the local truckstop are wives, moms, etc and many of them have had rough lives, so they deserve a little sunshine during their day. I don't demand anything, I always try to ask politely and give the benefit of the doubt. If a server is out of sorts, I'll give him or her a pass the first time. We all have lousy days, right? If they're always that way, I avoid sitting in their area if at all possible.
If the service stinks, I leave about 5%. Not tipping is not nearly as effective in getting their attention as half a tip, as I've been told by people who work in food service. I can appreciate a server who has been on his or her feet for several hours before I get there and still can smile and be pleasant and does a good job serving me. The girls at the local truckstop are wives, moms, etc and many of them have had rough lives, so they deserve a little sunshine during their day. I don't demand anything, I always try to ask politely and give the benefit of the doubt. If a server is out of sorts, I'll give him or her a pass the first time. We all have lousy days, right? If they're always that way, I avoid sitting in their area if at all possible.