I climbed Theilson last year, in the summer. One person in our group had climbed it before and talked it up as a major undertaking. I had checked some books and what I read didn't match this dudes list, but decided to carry the gear he said we would need anyway. I had never climbed with this guy before or I would have known what a wanking wimp he was.
We sloged up the slope loaded with gear and soon I noticed we were the only ones with packs. When I got to the top and looked at the 4th class scramble and people going up it in tennis shoes I wanted to kill that dude. I had rock shoes and a harness in my pack that was just added weight and bulk. He showed up half and hour later with his friend and their wives and started roping up, busting out the gear, and asking who wanted to make the "lead". I just about puked. I scrambled up, looked around till I was bored, and headed down in time to pass these wankers "lead climbing", shoes and all.
The moral of the story, don't trust some body just because he said he's "been there, done that", research it yourself.