I think the conversation would go further and without animosity if you would indicate why you don't believe things to be true.
Actually, with respect, I disagree. I believe some folks would use this reply as a launching point to quibble about minutia details that have nothing to do with the point I'm making. However, I'll let you prove me wrong about that...
http://www.drdaveanddee.com/tipping.html
AT THE RESTAURANT: ... Waiters: 15-20% of the bill, unless a gratuity is already added to the bill.
http://seattletimes.nwsource.com/html/foodwine/2003826000_taste08.html
Bob Knudson gladly leaves a 15 percent tip when he dines out — 20 percent if service is exceptional.
http://www.findalink.net/tippingetiquette.php
Food server - 15-20%.
http://www.pctoday.com/editorial/article.asp?article=articles/2007/t0502/26t02/26t02.asp&guid=
In a restaurant, tipping servers is obvious
—15 to 20% of the bill
http://www.magazineusa.com/us/info/show.aspx?unit=travelinfo&doc=6
In restaurants it's usual to give 15% tip on the total amount.
http://marketplace.sfgate.com/22Z9TN
which will put you right in the ballpark of tipping 15-20%.
http://www.bremercommunications.com/Tipping.htm
In fine-dining establishments, there are a number of people to tip. Servers expect 15%-20% of the pre-tax amount of the bill.
http://www.azaz.essortment.com/tipping_rdef.htm
Server at a full-service restaurant – 15% to 20% of your total bill.
http://www.getrichslowly.org/blog/2006/10/12/basic-tips-on-tipping-how-much-and-to-whom/Waiter 15% for adequate service, 20% for exceptional service. For poor
service, leave 10% or less.
http://hotels.about.com/od/hotelsecrets/a/tipping_2.htm
Waitstaff -- 15-20% of the bill, excluding tax and expensive wine.
And keep in mind that the point isn't that any of these are a definitive source but rather that the "vast majority" of all comparative statements mention 15%, not 18%, as the bottom of the range. Also, I'm STILL and will continue to talk about the assertion with regard to the general case. No one cares about what is the case in one specific restaurant. The original poster has already acknowledged that his own personal experience does apply there. Please accept that as well.