I pug basically all of the time. Last night I played a series of 3v3, I think 4 in a row and won all, and even though many of the same players played a few games in a row, we moved teams around a bit, I never checked the stats of anyone, and we all had some fun.
One thing that annoys me is a stacked/premade team, you play against, your 6 game old noob drops 8 mins in after feeding, and you and the other guy continue on, and after holding them off for quite a while till both sides had giants going and lv19 for me, the other guy said we did well against a stacked side and with an AI on our team, the response from the other side was "If you don't want to play with AI just quit then", "It is a team game!", "You noobs etc etc...".
THen again they did use the standard stack build of the 3 most seemingly powerful DGs, Oak/LE/UB, and just insta ganking everyone, obviously using vent/TS, but we didn't complain. We just played got a few kills etc, did pretty well against a team that was obviously noob stomping to boost stats.
I wouldn't of minded if they weren't tools/a******s about it, but when they get all stuck up about it, I tend to not want to play with them anymore.