In regards to the original poster i would say let this be more of an example of the extreme bad that can happen with free beats and not necessarily the norm. the problem isn't automatically that your giving away free beats and thus devaluing yourself as much as it is not making a real connection with anybody.
going on website to mass advertise a beat or collab usually doesn't lead to anything substantial as far as networking goes. usually best you get are a bunch of worthless comments ("beat sucks", "beats hot now check out mine" etc) and the occassional guy that comes up and takes the download but doesn't give you a version of the finish project. It will probably be on someones mixtape in alabama somewhere and you won't know anything about it let alone be able to use it on your resume and being that 99% of the time getting free beats out is in an effort to build a track record to establish yourself, isn't really helpful.
I am in no way saying that you have to personally shake every rappers hand that you want to work with, what i am saying is find a more personal way to make connectioins on the net.
its 2011 and every artist you could imagine is available on twitter, good ones. Your tracks are good, why waste your energy and craft on no name scrub artist most of whom you haven't even heard to determine if they even know how to rap.
I know when people first get in the producer game (im not talking specifically to you sf, you could be a vet for all i know) they're main concern is making sure there music isn't stolen, that beats aren't taken without proper payment or credit. the worry should be that you have subpar artist on good beats since thats 10X worse.
im pretty sure none of them cats on that forum are anybody you'd want to put on a song to have represent your production skills. don't sweat it.