Scientists often cheat. Bad and famous scientists cheat. The cheating can be small or large: putting your name as an author on a paper that you barely read, omitting part of the an experiment, making up experimental results, claiming that you have a proof of a given result, making something look more complicated than it really is, and so on.
Cheating can serve you well. It may help you get a larger grant, a better job, and so on. However, all these gains are short term ones. For longer term goals, I believe cheating eventually makes you less relevant.
This idea came to me as I was reading a comment on this blog:
A scientist or mathematician may achieve relevance as a side-effect of aiming for rigour. (Peter Turney, somewhere on this blog)
Update: One of my colleague has written a book on scientific frauds (in French). Thanks to Sébastien Paquet for the link.