Originally Posted by
kawaii
You're a good man, Charlie Brown.
With regard to Shanghai, my two primary cards are Bocom dual currency and my corporate Amex, so I haven't encountered DCC as an issue. In the cases where I've used my CSP (usually restaurants or hotels), I try to watch carefully for it on the receipt and whatnot, and I recall only seeing it a handful of times.
Shanghai honestly isn't so bad these days because many of the larger acquirers are now compliant (and 交行/国行 have a small footprint here), but if you chance upon HSBC, prepare for a battle (HSBC is small but its niche happens to be merchants that we foreigners frequent).