Through Alibaba and globalsource, you can easily find factories from developing countries. However, they do not guarantee the factory you find there is an appropriate match for you. Should you evaluate a factory during your factory visit? Instead of seeing what the factory says they can provide you with, (which is always the sales pitch!), try to do some research on the factory facts. This is not something a factory can hide! Here are some hints:

Check their customer profile

Based on the customer information, you can evaluate the "standard" and "level" of fashion product they make. If you target at selling a T-shirt for US$20, you would not consider a factory who makes T-shirt for Agnes B? This is not about if they can make a T-shirt to your standards, it is about whether you can afford the cost of making a T-shirt at the cost of Agnes B while selling at US$20.

Check their production volume against production capacity

Most factories profile will tell you how many pieces of garment they make each year. However, how can you assure it is not made by third party (outsourcing)? Check the total number of machines they have in the factory, against the garment pieces made per year; do they have enough machines to make the number of t-shirts that are leaving the factory?! Outsourcing is not a bad thing, but you should consider it in your evaluation! There's no guarantee of the same quality should their outsourcing relationship break!

Check whether they have raw material (fabric & trim) suppliers nearby

Unless you have nominated suppliers from your end, factories normally will prefer raw material suppliers nearby. It has two benefits,

i) No or little transportation cost (time and money)
ii) Easy communication (face to face)

Even you don't use these suppliers on your bulk order, at least you can easily find substitutes for your garment sample before production

Check the factories inventory

Inventory comes when

i) The factory has over-purchased materials. These over-purchased material costs will be merged into your order. You will probably be overcharged
ii) The factory has canceled orders. Why does the factory have cancelled orders?

These are just few hints I found based on my previous experience working in factories operation. May be you can tell me more about yours?