1) Waiter is rude, or lacking in manners, or generally display bad altitude (sighing, rolling eyeballs)
Depends on when the bad attitude starts.
I.E. some friends and I went to a restaurant sat down the waiter serving us a little older than I ( around 25 then) walked by and lobbed the menus on our table and kept on walking knocking my friends cutlery around. We decided to go somewhere else but before we did I asked for the manager and explained why we were leaving. No matter what is offered as restitution, leave.
If the bad attitude starts after the meal has been ordered or well under way, my normal standard of tipping 20%+ drops to 5%, just to enough for him or her to pay into any sort of tip pool system he or she may have to pay into at their end of their shift and before I leave explain why they are getting such a low tip. I guarantee you the attitude will adjust for their next table.
2) Waiter mixed up the orders, but food comes on time…
Not a problem, but wont eat whats served to me. Not what I ordered.
3) Your order has been forgotten and you have been left waiting for 15 to 30 minutes (and is expected to wait another 10 for the food to come)
If its busy in the restaurant and I see the staff are busting their asses, I understand no problem. Something usually gets comped anyways. Might even tip them more because I know what its like to bust your ass in a busy restaurant.
If the restaurant is not busy, that’s when my slacker alarm goes off. That usually means at least 1 or more people don’t give a shit your in the restaurant. If they don’t give a shit about getting my money its safe to say there’s a good chance they don’t give a shit on how they prepare/handle your food either. Low tip again. Probably wont be back.
4) You found something mildly icky, like hair in your food; or that the food is unsatisfactory (too salty, the beef is not at the done-ness you want)
Foreign objects in my food, it goes back.
If the food is objectional, the only thing I’ll send back is if something is under/over cooked or its way to salty, I’m 40 and want to live as long as I can. I realize that some food in some restaurants are really bland or just plain weird, those are just bad cooks, will take note and not likely go back for awhile.
5) You found something considerably icky in your food.
Foreign objects in my food, it goes back.