If you join one of these games just to be a noob basher...then Fritobag applauds your efforts and wishes you to rape more noobs.
As a matter of fact, if they say no rush 30 minutes I give you permission to flame them from the start of the game and then proceed to rape them.
If they don't wanna play competitively, you show em who's boss and kill their confidence, spirit, and make them want to quit starcraft and commit suicide. Go you!
But the games where the title are, "1v1 Come Zerg" and such make sure you only join if you are going to play the race the host specifies. It's legitimate because the host wants to practice against that particular race so please don't waste their time. You can always join another game. It's really annoying when I make a game called "1v1 Terran Vs Zerg" because I want to practice that match-up and then the kid thinks it's funny to change his race at the last second and make me remake the game...
Otherwise, proceed to flaming, pwning, and destroying the confidence of noobs! Fritobag encourages you! Continue the noob bashing! FEEL DA POWER RISE INSIDE YOU.
"Those who would give up Essential Liberty to purchase a little Temporary Safety, deserve neither Liberty nor Safety." -Benjamin Franklin.
I offer SC2 coaching for $25/hr, msg if interested