For a 10 day game jam, if you find a game that looks super polished, detailed and complete, then it probably wasn't built purely during or for this particular jam. That said I try to evaluate each entry on its merits for the time a team has to produce it. Unpolished buggy games can still have really innovative concepts which are fun to experience and I have found a couple during this jam that I actually spent 30+ minutes playing. You get aesthetically very pleasing entries that aren't much fun etc. so there is a degree of relativity but on a 5 star scale I'm thinking by category is it average (3 stars), better than average (4 stars), mind blowing or exceptional (5 stars), or less than average/very pooly implemented (2 stars). If its devoid of a criteria, thats the only time I'd give it a 1.