i like that project and it would be cool if it succeeds. but how will they prevent people from selling alot of illegal stuff? that would hurt it open bazaars reputation.

Well you can't prevent it, people will do as they wish. We can only hope that positives will outweigh negatives.
Personally, I really like the project and I think this is a nice chance for Bitcoin to shine. Design of the Bazaar is really nice in my opinion.
Can't wait for it to completely shine so I never again enter Ebay and Amazon.