Basically, playing pubs in dota is like playing against people who spam up B with Link in smash. It makes you worse =/
But there's this pro inhouse/league channel you can try-out for called TDA (there's actually a few of them but I think TDA was the most popular). If you get in you can basically scrim against any top team in the nation, although if you consistently suck they kick you out and you have to try out again (which I don't understand, because you can't really get better without participating in scrims, but it's hard to get contacts for a scrim unless you're in a league) but it's the equivalent of playing with Ken, Azen, M2K, etc. so you'll get better really fast.
I think you can search/post in the main DotA forums to find out how to contact a TDA member.
EDIT: Who's Plairnkk?