I notice that Slothrop's constant sexual encounters make me take him less seriously as a character. This is not just because it makes him, as my friends and I like to say, a "man whore".
Slothrop's relationship to Katje was set up as "special". That is, he seemed to really care about her and Pynchon spent more time talking about them. Slothrop even talks about missing her. Yet he goes on to have sex with anything (female and human) that moves. So this means he has a complete disconnect between sex and emotional attachment, or he really doesn't care that much. I think it's amusing that, for someone so paranoid, he doesn't really hesitate to have sex...well, I guess since it seems meaningless to him in the long run, it does make sense.