i have seen the other threads about guild reputation and i didnt see this information it them. neither do i know if this is intended or is a bug from blizzard after the last patch.
here it comes:
as you all know your guild reputation is capped each week so you max can get 3500 a week.
what i noticed is that when you hit 3500 then leave the guild and get invited back into the same guild. your reputation will still be the same but the experience and reputation counter is now reset so you can earn another 3500 in the same week.
if someone else has posted this then i havent searched good enough and this thread can ofc be deleted.