As a rule, I don't punish Assumpta. The only problems I ever really had with her were snapping and swatting...just aggressiveness towards people (which was understandable). Teaching her "No bites" and "no paws" helped with that. I've never had a problem with her scratching furniture or speakers...she tried each a couple of times, stopped when she was told (usually with a light touch on her paws), and never showed a big interest in them again (though a couple of times she has scratched the couch when under stress, like a visiting dog or child, but I know she's just trying to mark HER space, so I just ask her politely to stop and she does). The only time she really gets punished (which is a light tap with three fingers on her hind quarters) is when she's doing something that could physically hurt her (the only two times I recall doing this were when she jumped up on the woodstove when it was cold, and the time that she crawled into the furnace ductwork when we were rerouting a line). Because it happens so seldom, it's very effective. The water is useless for me, because I can never find the water bottle in time, and she knows it's me doing it anyways. In general, I just ask her to do things politely, and she complies. I'm just lucky, I guess.
I'm not too fussy about dining room table...I do prefer her off the kitchcn counters...it hasn't been a huge problem, though I'm sure she occasionally tap-dances on the counter when I'm not around...but it doesn't bug me THAT much. I figure if she's smart enough to get around the rules, more power to her (I am a well-trained owner).
One thing you can try is a strip of "Sticky Paws" on the edges of the table or counter you want to keep the cat from using...cats hate it when their paws land in something icky at the end of a jump and it may solve the problem fairly quickly. They also make spray-on cat repellents, alarms that go off when the cat goes someplace he's not supposed to, and mats/strips that emit a small electrostatic charge that animals don't like.