I will add to the list -

Another issue regarding plane tickets that is being discussed on the Chinese discussion sites is that they sell you one leg of a multi-leg ticket, then get the refund themselves.

For example, you want Shanghai-Beijing. This is popular and expensive.

Ctrip secretly sells you Shanghai-Beijing-Dalian, which is much cheaper

After you fly, they can sometimes even refund the Beijing-Dalian portion.

I personally don't like the fact that I don't get to see the actual fare class while booking.