Wash never thought much about Simon either. In truth Wash was a simple man, he loved Zoe and he loved flying, anything else in life could be greeted with a laugh and a joke; well almost anything. Not to say Wash didn't like Simon but he never spent much time thinking about the man, until the night Simon told him about how he rescued River from the Academy. It had been not long after the fight at Niska's Skyplex, Wash had been on the bridge while the rest of the crew slept. Simon had wandered up and they'd got talking. That was when Simon stopped making sense to Wash.
See Wash had laughed at Simon's blundering attempts at deception on Higgins Moon and the way he always put his foot in his mouth talking to Kaylee. And he just couldn't square that with a man who bluffed his way into a top secret Alliance facility with nothing more than a forged ident card, a stolen uniform and a stun grenade. So Simon didn't make sense to Wash and while he didn't mind not understanding the man he hadn't missed the way Zoe looked at the Doc, like he was threat. So Wash may have liked Simon, may have laughed and joked with him, but he wasn't sure he trusted him.