I believe trader rating is bs.
The number of posts means nothing.Just look at what people post instead of the number.
Many people here post answers to get more credibility and/or to promote their domains,which this site allows to be posted everytime("signature").
Everybody has read how important it is for googlerankings and such to participate in forums and put your domains in the signature.So self promotion is key.I would definitely value contributions without domains in the signature more than others.
Just like with bloggers you never know what people are up to and what the value of their text is.Look also at a site like domaining.com,which get contributions from people from people who only are there to sell their domains/product.You believe they do not get paid for that?
Shameless selfpromotion and promotion of products for which they get "kick-backs" are being promoted here and on all kind of blogs,all infomercials.
Regarding trust.I would rather trust a newbie than a senior. From my experience in the pokerworld, people do not f*** you the first time around for substantial amounts .The people who have been around and appear to have credibility get you for the bigger amounts.
Newbies may f.. you for 20 dollar, so what.
Also do not forget people who have been around may be looking for ways out or have gotten into financial trouble.
In case something happens other senior members prefer to believe one of their own vs a newbie, so trusting a senior member as a newbie is not a good idea.
Just trust nobody is the best idea, just decide for what amount you do not mind too much be f'd and have everything else be arranged by escrow. If you are looking for margins where the escrow fee makes a huge difference, you might be better off working for a salary instead off spending much time on this.