Online shops user opinions firefox addon?

[justice]

Whenever i'm shopping online I want to know if the website with the good deal is reputable. It's possible to google for shop + scam, and check the mcafee siteadvisor (or start a topic in your fav forum) but I was wondering if there are any websites that are not marketing driven with honest user reviews of shopping websites (like ebay's feedback system).

Bonus points for any firefox addon integration for easy access / discussion.

If not is this a good idea for a new site?

[justice]

Just to be clear:
I'm not just looking for security information (although obviously it would be beneficial) of the site.
I'm not looking at reviewcentre / ciao or price comparison sites with comments filled by shop employees.
When I find a deal I need to know something like: "quick service, reliable", "good packaging, would recommend" and 500 transactions (98% positive)