I have twice had seatmates so drunk that they were arrested. One groped me prior to takeoff and the flight attendant did nothing to reseat me. Upon landing, once the pilot found out, he flipped a lid and had the guy arrested.

After that incident, I no longer put up with the smell of booze. Next time a guy sat next to me so intoxicated I could smell it, I alerted the flight attendant, who simply had him removed (and subsequently arrested) before takeoff.

I have only been flying frequently for about two years now, and I've seen TONS of examples. If you've seen suprisingly few, you are either lucky, or you have thicker skin than I.