To me, service is something that a person can control. If a person along the way screwed up, skipped a step, was lazy, etc., then it's bad service. Everything else... is just bad luck.
Waitress takes 10 minutes to bring a table the check because she's dicking around in the back/ forgot to print it/ is just shitty at handling several tables? Bad service-- even if it's just because she's busy, taking forever to bring a table the check is bad service.
Waitress takes 10 minutes to bring a table the check because the computer system went down in the middle of the rush on a Saturday night, the repairman can't be reached, and she has to look up the price of everything, hand-write it in a legible fashion, and add it up on a calculator (including tax) in addition to handling four other tables? Shit happens, unless you count bad service on behalf of the computer company for not making an infallible system or the repairman for being off on weekends.
Customer requests steak to be cooked medium-rare, and the steak comes out looking like a piece of shoe leather? Bad service-- SOMEONE should have caught the mistake, be it the grill cook, the expo, or the server who brought the food out.
Customer requests steak to be cooked medium and it comes out medium-rare (or vice versa)? Shit happens-- sometimes even the best grill cook can't accurately gauge what temperature a steak is by looking at the outside.
Server doesn't write down a table's salad dressings and brings a customer the wrong salad? Bad service.
Server mishears the customer's request for "French" as "Ranch" and brings the wrong salad? Shit happens-- this is assuming the server repeated "Ranch" back to the customer and the customer also misheard (I've had this happen often... of course the customer rarely admits his/her half of the error, but that's a rant for a different community).
Table's food takes ages to get to the table because the server forgot to ring it in? Bad service.
Table's food takes ages to get to the table because the ticket was rung in right behind a party of 12's food? Shit happens.
All of these situations cause aggravation, but only some could have reasonably been avoided. Should they be treated accordingly? Is the experience measured by the outcome, or the steps leading up to it?
What do you think?