After a few things I've read here and on the chan:
Please try to take it easy when commenting existing models and new submission. You can tell you think they don't look good and how they could be improved. But if sarcastic and useless comment like "look a dildo LULZ" or "Lrn to smooth" can be at least kept out the dev. channel (official forum, irc) It would be really nice.
Mikeplus, JoJo and HiveKnight get allot of unpaid work to make the game releasable, please try to keep the comments respectful and diplomat.
I happened to be quite a bitch myself sometimes, so I'll also try to keep it down.
If you need a complete and detailed tutorial on how to give opinion, please re-read this one :
viewtopic.php?f=72&t=4171