Possibly the biggest, most universally believed, and most ridiculous sexual myth about men is the belief that there is no such thing as bad sex for a man. This is so strongly codified in myth, legend, and entertainment that it even has men believing it. But there's more to sex than orgasm, and even if there wasn't, there are orgasms, and then there are ORGASMS. They are certainly not all the same, as anyone who's ever had one -- hmm, better make that two -- can tell you. Sex can be as much the emotional as the physical, and good sex often is -- But not always.
Pseudo_Intellectual mentioned to me that I might want to consider mentioning something about the difference between orgasm and ejaculation. While it's a deviation from my original point, it is another excellent sexual myth to point out. There is a strong belief that there is no male orgasm which does not include ejaculation. This is untrue. The most common (or acknowledged) cause for this is "running dry" after having a significant number of orgasms, which is known as firing blanks. However, it is possible to have an orgasm whose associated muscular contractions are not strong enough to propel semen from the body.
Part of the reason for the propagation of such myths is almost certainly the awkwardness that most people feel when discussing anything of a sexual nature, especially if they feel that there is chance that they might hurt the other party. If the meat of what you are trying to import to your partner is that what they are doing is not what works best for you, it is somewhat natural to feel awkward. Most of us have been trained not to speak freely about sex by our parents, our educators, and the media.
In addition, the sensationalist media propagates myths about both genders freely. The much-maligned so-called "women's magazines" like Cosmopolitan (The usual favorite target,) which present articles on "how to drive your man wild" and the like, make it seem as if all men were the same, and of course they are not, psychologically or physically. One lady once told me that she had read in one such magazine a suggestion that the woman address the penis directly, and tell it what she was going to do to it, because men would find it to be "hot". We did get quite a few laughs out of the idea, but I certainly did not find it exciting. While this is an example of the triumph of free thinking and a willingness to be open with one's partner, it could easily have gone the other way, and almost certainly has, with other couples. How do you react when someone does something during sex which you find not only unappealing, but frankly ridiculous?
As always, the way to avoid the maintenance of such myths is to avoid making assumptions, and to communicate with not only your partner, but anyone else you can bring yourself to feel comfortable with. Asking and answering questions is still one of the best ways to get a point across, and real time communication allows one to ask for further clarification. Sex tends to engender strong feelings, so a lack of communication can turn into a significant problem. The more you learn, the more you can share with others, and the more willing you are to share, the more all can be enriched.