Keep surfing this site. There are all kinds of discussions about new guys flying EZs, how they handle, and what it takes to fly them.
I believe that you will also find all kinds of stuff in here about quality of workmanship.
Recently there were discussions on people selling EZs----and those types of people you should avoid.
When you are ready, you can probably find a person to inspect for you. But in a nutshell...did the builder use the right number of layers or fiberglass or not? You will never know unless you cut the part in half and take a look. However, those builders with good reputations, those that meticulously documented their project (including pictures----see Wayne Hick's site as an example), those with planes that have a fair number of hours on them (proven), plus a whole host of other indicators can give you a good indication of how good the airplane is.
The one warning I give to potential buyers-----don't think you can avoid getting your hands dirty by buying an already built fiberglass airplane. Be prepared to learn a lot about fiberglass, epoxy, engines, hardware, etc. If you don't like working with your hands, or don't have time to learn about these machines------then experimental aviation is not for you----or if you have lots of money, you can probably get someone to take care of it for you.
If you surf this site (as well as canardzone.com) you will find all the answers you are looking for.