I bought some 0.7mm bits from China out of curiosity. They are not even worth using. They dance all over the board.
I've used (and sold) many micro drill bits sourced from china, with no problem, from 0.7mm to 1.4mm (mostly 0.8mm).
Perhaps it is helpful that I etch then drill with a hand held motor, and so have an etched hole in the copper for the bits and more control, but I've not really thought "man this is unusable dancing all over the board", indeed they go through my pcbs (copper or not) like the proverbial knife through butter - as long as the motor is running fast enough.
The ones I get come in orange labelled tubes, and I use them primarily hand held in a cheap brass collett attached to a 24v DC motor ripped out of a printer.