I can recall some horror stories of badly behaving JWs at restaurants.
I remember how some pioneers would take up diner booths and order only water and then eat their bag lunch and then leave a pittance of a tip. Not only was that hurting the server, it was hurting the restaurant owner. They count on people spending money at those tables and turning them over so many times in a meal period. When free-loaders squat and don't order anything, it hurts the entire operation. One diner owner complained to a brother who was a regular as a construction worker not knowing he was a JW. He went back and said something to the pioneers, not to talk bad about the diner owner but to remind the pioneers that they needed to be better customers. Of course the pioneers got mad and boycotted the place from then on. The diner owner was ecstatic, I'm sure.
When I was a kid I remember some dubs leaving magazines as a tip in a restaurant but the practice fell into disfavor sometime later. The WTS has printed guidelines on not doing that even. But even as a kid, I was puzzled by such a practice. Even then I knew that waitresses relied on tips to help supplement their crappy per-hour pay.
My JW in-laws are cheap. They are the worst tippers. They prefer to eat at places where they don't have to tip...at least they know they're cheap... but on occasion when we do eat at a full service restuarant, my F-I-L will always insist on picking up the tab, but then I have to go find the server and slip them another 10 bucks or so to make sure he/she was tipped properly. We finally got him to let us leave the tip since he insisted on picking up the tab. But then my M-I-L would bitch about how much I was leaving. So again, I just started handing the server the money personally so she couldn't carry one about it.
But having said all that, I knew of JWs who were good customers....loyal customers...and tipped properly. I remember for several years at one hall where we went to a local pizza parlor after the meeting every week and the staff came to know us. The owner would come out and chat with us. The servers were always glad to see us. They would ask if someone was missing. And we knew to tip well and treat them well. And to our credit, thankfully, no one ever tried to witness to the servers or owner.
Another hall and time, we used to go to a local deli after the Sunday meeting. No tipping required, but there would be anywhere from 15 to 30 JWs lined up to order and we'd drink beer which the Baptists who also came in after services wouldn't do. So we helped the owner's beer sales. We came to know the owner and his top staff. They treated us well and would give us free apps from time to time just for being such loyal customers. We always cleaned up well behind ourselves and re-arranged the furniture back to the way it normally is instead of just leaving them all pushed together. The busboy always thanked us for helping him.
So - not all JWs are no-tipping, cheapass, lowclass customers. While there are some, there are others who were the exact opposite.
People tend to remember the bad customer rather than the good ones. I'ved worked in the service industry. I can recall the bad experiences much better than I can the good ones. But the good ones actually outnumbered the bad ones.
I think another thing that helps give the JWs as a group a bad rep in this area is that most JWs are working class stiffs themselves. Most don't have extra income laying around. They're struggling to make ends meet. Not a lot of college grads in those groups of dubs that come in. So many of them count their pennies much closer than the average group that comes in. So you probably will not see a lot of big spenders and big tippers in their ranks.
Speaking of college...one place I worked at, all the servers hated the college kids that came in as customers. They were the absolute worst. Ordered you around like servants, would hang out at a table long after the meal was done, thus eliminating being able to turn that table over, bitch when we wouldn't serve em booze if they forgot their ID and then leave next to nothing in a tip. These weren't working class college kids...they were kids from well-to-do families who weren't expected to work their way through school and they drove brand new BMWs or Audis because daddy had the money. I know that not all college kids were that snotty and rude, but enough came in like that, that the stereotype was developed and the servers dreaded seeing any group of college-aged kids come in. So we were guilty of lumping all kids into one group instead of taking it by a case by case situation. Same with JWs. I think some of us tend to focus on the negative conduct of the badly behaving ones and we tend to lump em all together and bad customers when it's not really the case.