A lot of Porn and or sex can definately de-sensitize you. I think if someone were to ejaculate say 5 times a day everyday for a month that person would find it very hard to really be turned on at the end of it all. Thats an extreme situation. The opposite end of the spectrum would be someone who hadn't ejaculated for a month, he would probably find himself easily turned on and feeling very horny most of the time. But I think things tend to sort themselves out after one lays off for a while. Too much of practically everything can be bad in high doeses.