Not everyone is honest or can provide the correct information, prices are not what they always advertise, but in general i would say 80% are here for business and are professional.
My good experience that Alibaba refunded my purchase when i had a bad deal and supplier could not fulfill my order.
The bad experience is the communications, some they take too long to reply and sometimes they never do, or if they do they provide the wrong information, be careful and be clever how to close deals.
I made many purchases (more than 2 containers and 5 LCL shipments and few by air) for my company and 95% are completed in perfect conditions.
In my opinion this is the best option in the market for business purchases.