The amount of the bill is the total bill before tax. There is no reason to tip on top of tax. If your meal or parts of your meal were complimentary due to mistakes made, gift certificates or management approval, a tip is still necessary and should be based upon what the bill would have been.
The only contact with the staff is for admittance and paying the bill.
The staff provides beverage service, frequently checks on the table and keeps silverware at hand.
Food is terrible, service is terrible and no one cares. Frequent responses from management include: "I'm sorry you feel that way" and "What do you want me to do about it?" It is okay to stiff your server in this case.
Service is barely there or is incredibly slow with mistakes. However, the food is good. Servers have to pay taxes on a base percentage and/or "tip out" to the kitchen, so this base amount is considered a "bad tip".
This is the low end of what you expected. Service was timely, but not fast. Food was good, but not excellent.
This is what you want as a minimum. Service is prompt and friendly, problems are quickly fixed and the food is oh-so-tasty.
The server accommodated all requests, no matter how odd. If there were any problems, they were fixed and the item comped. They gave excellent menu recommendations and you felt well taken care of.
The staff made you feel at home, just with better food and better service. An excellent rapport was established, they had an excellent knowledge of the food and drink menus and anticipated all needs. You would prefer to come back to this restaurant when this server is working again.
Similar to the experience from hell, however the management actually cares in this instance. Also, the server is apologetic about any mistakes made.