The Schmucks who have signed up a few hours or even a day or two before rating are obvious. How can they rate something that needs a week or a month steep when they haven't been around that long? Sure they could see and try the recipe without signing up but it seems fishy, lol.
The pay to play idea seems unfair because a lot of people are dead broke but they might have valuable input but a hardcore schmuck with a grudge might happily pay money to cause trouble. Also, tying it to forum post might not be fair either since some people shy away from social interaction. (like me half the time, lol.) It seems only fair to use a combination of factors though. Maybe something like, having their account for 30 days + 10 forum posts OR 60 days +10 public recipes OR 90 days for those folks who don't make their own recipes and don't socialize.
For what it might be worth, since I have so many recipes now I've started rating my own just to find the ones I'm working on or making a lot of. This isn't meant to indicate they're very good so most are still private. The ones that both my kids and I liked a lot are made public. For other people's recipes, I only look at the rating to try and tell the possibly failed experiments from the ones that worked out pretty well for people.