1. There you go, you put the bad-mouth on others.
2. There you go again, you put the bad-mouth on others.
(Are both the same in meaning? Which one is common?)
3. There you go. You're always forgetting things.
4. There you go again. You're always forgetting things.
(Which one is correct? Are both the same and okay? Which one is commonly used?)
I've never heard the phrase "you put the bad-mouth on others" before. Does it mean "you insulted others"?
In both 1 and 2, you have run-ons. You need to use periods after "go" and "again" not commas.
3 and 4 are correct.
4 is probably more commonly used.