It really depends on what kinds of goods your are purchasing.items like computer, need services in future, I think you have to visit factory, alibaba just offer a place for contact, beware of your eye. most buyers just buy normal quality goods,like tools, clothing, no need service, many factories ,companies in China,can supply,If you order is only few items,and in large quantity,you can deal with factory, or your order is many items in small quantity,I recommed you 'd better deal with trading company.first deals, you can open LC instead of TT.I think you also need to trust suppliers and factories in China. most of them are honest business.
if full of cheaters, then no people will using alibaba.