I've had people call me: cheater, coward, looser, and so on for achieving perpetual check or threefold repetition in a loosing position. I understand it may be frustrating for some, but those draws are only possible if the "victim" allows them.... so go cry to your mama dudes 
It happened to me too during a very offensive otb game with a random guy in the park. I was about to launch a mad attack on his king, but had to use 1 tempo to set the last piece in position. He saw what was coming and also the fact he could check me forever so he just said "I have no choice" and offered me a draw; so yes... that's chess and I can live with it.
If you can force something on the board etiquette does not come into it. Only time it's an issue is if you offer a draw and your opponent turns you down. It's not good form to keep offering a draw if your opponent does not want one.
Billy.