When you fake it, your partner gets the idea that he or she is doing things that work for you, when they don't.
I have probably faked a few times, (a LONG time ago) and it came back to bite me in the ass (not literally) because then the guy thought that technique worked for me, and then both of us were unhappy. I learned quickly that its better to be honest, and let him KNOW what works for me, what I don't care for, (or don't want just this one time) what I DO really like and he then learns what works to help me find my orgasm.
I don't believe in faking to save a partners' "feelings." They shouldn't get wrapped up in the idea of "making" someone else come anyway. Orgasm is a couples effort, not one person "making" an other come (unless you're using Forced Orgasm Play, in which it's even worse to fake it.) In most situations, the effort to bring one to orgasm should be shared.
Orgasm is an effort that both members of the partnership need to participate in, and letting your partner know what works and when will only help the relationship. If I don't like something, or something isn't' working in one particular session
I say something about it. Then we can move on to something that works for both of us.
I think one loses by faking it. It won't kill your partner if he or she knows you didn't have an orgasm. Letting them know what will work is much better tactic to get what you need as well as being honest with your partner.