This is true that if you have a darker complexion they might think you are a gypsy.
Outside of that that, from what I have heard, asians do not experience too many issues in Prague, with the possible exception if you are of SE Asian decent, specifically Vietnamese. This is because apparently there is a fairly large working class vietnamese community in Prague in addition to numerous immigrant workers from Vietnam and some locals consider them with a similar disdain you see other poorer visible minority working groups in any country (think Mexicans in the US or Muslims/Arabs in Europe)
Outside of that that, from what I have heard, asians do not experience too many issues in Prague, with the possible exception if you are of SE Asian decent, specifically Vietnamese. This is because apparently there is a fairly large working class vietnamese community in Prague in addition to numerous immigrant workers from Vietnam and some locals consider them with a similar disdain you see other poorer visible minority working groups in any country (think Mexicans in the US or Muslims/Arabs in Europe)