Yeah, the leg-humping scene was pretty bad. It's degrading to the director or the writers or whoevers crappy idea it was, and vaguely insulting to the audience. When I go to see a movie, I go expecting something more than fart/masturbation jokes and sound effects.
Which robots were cussing? The twins? They were pretty annoying too, though they did have one or two amusing lines. Honestly, I don't blame the NAACP or whoever for being offended. I felt it was pretty blatantly disrespectful; an obvious parody of black men. One of them had a gold tooth. Really? A gold tooth? Was that necessary? Was his "real" tooth knocked out in a fistfight with his brother? Couldn't afford an implant?

At least they lived longer than the "black" robot in the previous movie. Poor Jazz lasted about 3.7 seconds before getting stomped by Megatron. I think he had one line in the whole movie, and it was probably something disappointingly stereotypical.