Tips

Friday evening I attended a happy hour which was in honor for a coworker who was leaving the company to run a sushi restraurant and a fast food franchise. A table in the pub cleared, so some co workers and I went to sit at the table. We noticed that the bill was on the table for the previous 2 people who were sitting at the table. Their bill was for $70, but they only left the waitress a $4 tip. This got me wonderering, why would people leave such a low tip, are they being fruggle, was the service bad, or are they just being cheap. The people who the bill was for had a decently prived wine bottle, had some cigars, and other various drinks. Just from that I figured they must not be that cheap. A coworker who I was sitting with, had a friend of his sit with us as well. His friend saw the bill and pretty said "what the heck, only a $4 tip, that is messed up". His dsguist in the tip led him to change the tip and total amount, which I thought was nice but then again the pub might be blamed for such a false action, which is bad. This friend of my coworkers, made the tip to be $24 and added a few strokes to make the total $94. He meant to do this to be nice, but then again when the previous customers check their credit card bill, they may fight the charge. Anyways though I was wondering what do other fruggle people think a good tip amount should be?