Morning Bob
You are absolutely right about the problems with cheap Chinese plywood, in my opinion its only fit for making concrete shuttering.
You have to be so careful when buying plywood for boat building as some retailers are trying to pass off the cheap imports as quality material (and charging quality prices)
I had a look around the local DIY superstore and was flabbergasted at the amount of inferior materials that were being sold. Some of the 2×2 par was full of shakes and so twisted that it was only fit for firewood
I shall stick to buying from timber merchants where there is a better choice, a far superior quality and believe or not better prices, for example I bought an 8ft x 4ft sheet of ¼ exterior ply for £6.00.
Paul