What would be considered "evidence of adequate funds" for entering Hong Kong?

I've only ever had to show this when reentering Mexico from a sidetrip to Central America, or when extending my tourist visa in Mexico.

It's been a few years (six to eight) but at that time they always accepted a printout of my bank balance from my bank's online banking website, and even just having a credit card. There was no attempt to verify the printout wasn't photoshopped or that the credit card wasn't maxed out.

Others have explained what “evidence of adequate funds” is in general but for Hong Kong specifically, none of this seem to really matter in practice. Traveling on a European passport, got in by plane, went to Macao and back by ferry, my passport and those of other people traveling with me were stamped quickly every time without asking much or looking at any documentation (not even the return ticket as far as I remember, I think I got a little form to return when leaving).

All this is obviously anecdotal but they did check passports' validity and a Turkish acquaintance faced real problems in Macao because his passport would expire before the end of the 90 days allowed.

I do not know if US passport holders are treated differently but the rules are apparently the same (90 days of visa free stay).