The rules are unwritten, and change often. The best way to do this, is to read ALOT of dinner pic posts. This is easier if your a team member <hint hint>
All posts start off with a "10". Points are then deducted from there. Judging is ruthless, assinine, subjective, anal, and anything but fair - unless you have a scantily clad babe in your pic. Having your wife/gf posing half naked in the pic is guaranteed to improve your score.
I repeat, having your wife/gf posting half naked will forgive all other dinner pic transgrssions.
For the record, I believe that having your wife/gf in the pic will help your score.
Before I leave, I'd just like to point out that scantily clad women have been received well in the past.
Word around the forums is, the new dinner pic standard involves hot women.