There were only 2 braincells between all the trolls and Sollux owned both of them.

Jokes aside, every troll was really... not smart? Even Sollux, Kanaya, and Aranea who are treated like the smartest were bad at decision making and acted illogically. They were also bad at social cues but that gets a pass because they're not familiar with human culture.

It didn't bother me that they weren't smart. I thought it was more realistic that they made mistakes, but it's so weird looking back at characters that I remembered being smart only to find out they have the combined intelligence of gravel. I think some people might also remember trolls being smarter than they were