In the long run, it’s quality and not quality.
I was always in one of the top 3 SERP’s for the keyword “slot tips” in both Google and Yahoo for years, up until about 18-20 months ago and I just had a few inbound/outbound links.
It just seems there are so many more gambling sites now than there was a few years ago. Don’t remember reading about all the sleezy tactics there seems to be now. but maybe I was just under a rock or something.