Quoted from VDrums2112:

I nudge my games all the time. I'll nudge tournament games all the time. If at a friends house, I'll observe how they play their games. If they nudge, I nudge. If they don't, I ask if nudging is OK. If they prefer I don't then that's fine, no big deal. I can have fun playing either way.
Some people consider nudging cheating or abusive to the game. To me it's just the way the game is played. Before flippers, how would the player manipulate the ball? Nudging, right? Skillful nudging is perfectly acceptable and part of how the game is played. Now if you're smacking the back box into the wall then yes, obviously that's abusive and unnecessary to get the ball to do what you want. But nudging, forward pushing and slap saving I don't consider abusive or cheating. A properly set tilt keeps you in check as to what you can get by with.
-Steve