I've spent a fair amount of time interviewing in London a few years ago. I would literally go to any company that send me an e-mail or contacted me via recruiters.

I didn't have enough money to buy new clothes at the time, so instead I've picked the shoes with the largest amount of holes and would never do any grooming before hands. I would come stoned to the interview. So the gist: instead of trying to appear on the lower mid end, I went all the way through to the lowest low end.

Thinking retrospectively I think that's pretty much the reason why I barely received any negative responses unless I had miserably failed at the technical side of things (e.g. I didn't know how to use generators in Python at the time and the whole list of questions would be about them and their syntax).

I have to admit that in this scenario I was quite good at the technical side of things. But the general philosophy was that if I don't try to appear too good - people will assume that I was better. Put humility and definite sprinkle of character on top of that.