So my biggest issue with Wesley was what an elitist douchebag he could be. He would openly disparage non-Starfleet people, in a way that was at least unprofessional, and at worst outright insulting (like the shuttle pilot picking them up for that crash-on-a-deset-planet episode).
And at the same time, he sucked up to the people above him or who could help his career so unabashedly.