At least, the ones I've been to all did what I requested.

As far as I can remember:

*Ritz-Carlton Beijing Financial Street (the front desk staff told me Bank of China would come to them to do "sales" of DCC, but the guests of this brand are mostly 500 companies, and they don't wanna be fools, so the hotel would turn off DCC very willingly and professionally)
*Westin financial street Beijing
*Westin Chaoyang Beijing
*Sheraton Dongcheng Beijing
*InterContinental financial street Beijing
*InterContinental Beichen Beijing
*Crowne Plaza Beijing Sun Palace
*Crowne Plaza Beijing Chaoyang U-Town
*All Holiday Inns in Beijing
*Holiday Inn Express Wangjing Beijing
*Holiday Inn Downtown Shanghai
*Holiday Inn Express Zhabei Shanghai
*Renaissance Yuyuan Shanghai
*InterContinental Ruijin Shanghai (this one they used another POS which has no DCC, but I have to request the IHG points by phone from Chase)
*Holiday Inn Shijiazhuang (this one they didn't know to press cancel, but did so when I instruct without hesitation)

All of the POS I ran into in these hotels are from 交通银行, 中国银行, 工商银行, and UnionPay. 工行 and UnionPay don't have DCC (as far as I have encountered), and 交行 and 中行 can be turned off by pressing cancel right after pressing enter.

For smaller private business, they tend to wanna save on the swipe fee, so they would stand with the bank to DCC you. Just get a Discover to use in China.

P.S. I am trying to find a UnionPay sticker to put on my Discover, so people would not refuse it simply because these is no UnionPay sign. I've faced this... Once in IKEA, they swiped my card, thinking it is a foreign card, probably waiting for DCC to happen, but the POS machine act as they were swiping UnionPay cards. They panicked, held me for five minutes, trying to confirm they got the transaction for numerous times, then let me go.

The slip just says 银联卡 when you use Discover in China.