Anime: Sometimes
Manga: Most of the time (don't need to worry about the moaning being heard)
Some of the hentai anime is badly done, and most of the time only loosely follows the manga/VN they're based on, which is a let down because I played "Please Rape Me!" and found it interesting. When I sat down to watch the anime, I was rather disappointed with it. Although, they did do a good job with Chidori's rape scene, but outside that there was loose basis on the story line.
Hentai manga is usually the better of the latter. It has better production quality and better story line. Example, "Mirai Paradox", the storyline, although rather short, was interesting to me. Honestly, it was hardly fap material due to the fact that Mirai was his daughter, and his wife, Shizuka, is really his stepsister. Another examples of good h-manga, would be "Love Selection" and "Domin-8 Me!", both have good storylines and relatively good graphics.