The experiences that our members have with alibaba.com may vary from one member to the next as some may have found great suppliers while others may just have been scammed. We suggest that if you indeed decide to use the suppliers you mentioned, please do with extreme caution.
We do have several posts made by our members here in the forum and SaleHoo has written a blog particularly about Alibaba.com, here's the link to the blog:Link hidden: Login to view
Here are a couple of posts for your reference:Link hidden: Login to viewLink hidden: Login to view
You can actually search for more posts by using the 'Search Forum' option on the side menu.
Hope this helps! Cheers :)