Personally I would not have a problem if I saw a judge sitting with a competitior. They have boxes with numbers for a reason, and then they put different numbers on the box when you turn it in. It would be extremely difficult for a judge to figure out who it was. I have seen judges sitting with competitiors before and never thought twice, and they were wearing their name takes and a judges shirt.
People are just looking for something to complain about, if they got GC they would not complain. If they do poorly there are people that will complain how far away they were from the judges tent and multiple other things.
You can't make everyone happy all of the time. I understand that you don't want to give off the perception of favoritism. I would say hanging out the day before is ok, but the day of turn ins don't stop by until after judging is complete. Have a beer with our brothers in smoke and help clean up. That way no one could say that there was favoritism.
This is just MO.
1 Meadow Creek TS120 with chicken cooker
1 Weber Kettle