Bloo's a pretty funny character in my opinion. I commonly see people peeved off that Bloo acts like a jerk, but I believe that's part of what makes the show itself funny. Bloo essentially
is Foster's, and it wouldn't be the same without him.
I also found a
video essay on YouTube that explains why Bloo acts like a jerk. TLDW:
Spoiler Below Essentially, Bloo is traumatized by the events of House Of Bloo's and his friends didn't allow him to heal, instead only being able to see his bad side despite his good intentions, further locking in his bad reputation and resenting his friends more and more.
It definitely changed my perspective on his character.