I’ve joked about adding expensive stuff to the tab when my (cheap) friends offers to pay. But I didn’t really change my order, and find it surprising many other people would take advantage of the situation. Realistically, how often does this happen?
A lot of times and situations I don't care all that much and mostly adhere to the "things balance out" philosophy. If we go out with people for a burger and a couple of beers, who really cares (although nights like that are getting pricier these days)? Those nights are usually fun, and it's hard to rack up a huge bill (ie, people can't order a $68 steak paired with a $200 bottle of wine).
But when we go out to a fancy restaurant with people loaded to the gills talking about their 2-month trip to the Orient and their upcoming journey to Australia, I don't feel inclined to have to pay for them (no matter what they order).
Sometimes we have gone out with folks with kids just old enough to drink and they have conspired to keep buying alcohol and having too much to drink. That's a tough one, as they aren't going to offer to chip in, they get obnoxious, and I would be inclined to tell them they get one mixed drink and then have to switch to soft drinks. But the discussion then turns into "oooohhhhhh, we haven't seen these people in a while, what's the big deal?"
I'll give another example. With our kids, they are now all at the age where they are dating people, and when you add in multiple kids with multiple +1's, things add up quickly. Those type of situations get a bit awkward. I would usually pay for our kids (who have high paying jobs), but I'm not really sure I want to pay for the person that they've just started dating or have seen off and on (mostly off) for the past 3 years. Probably a different question, but at what age / stage in life should kids be expected to chip in when going out (or pay for their dates) . . . especially when they have established careers and make good money?