Oh, my word, I have had experience with Malaysians (good friends, I'm not slagging them!) and yeah, does tact get removed at birth?? LOL!
Unfortunately, my DS' Mayan heritage is diluted with Irish (half of what I am), and English (which, if you go by thinking in terms of the false concept of 'race', means he is really mixed 'race' right there!), so I don't really get comments about him...and I wish I did, because I'm losing my connection to that side of things! But I'd probably be really sick of it after the first day.
For myself, being half and half, the only comments I really got were when I was little, from other kids who called me 'Abo'...which disgusted me so vehemently because I thought 'what if I really was? How much more offensive would that be?', as well as "well I wish I was, cos that would be easier to explain, as well as being a great thing to 'own up' to" (geez, I was a bit progressive for a 7 year old, cos I clearly remember thinking that and talking about it with my parents).
I guess I have always existed on the fringes of 'mainstream', so I can tell you that your child will be able to overcome this rudeness (should it continue) and possibly even become a very resilient person because of it. It's an extra 'something' that you can turn into a blessing or a burden.
In more recent years my appearance causes confusion because sometimes I'll wear some pendants from New Zealand, so without clarifying what my heritage is people will just assume that's what it is and when something about NZ comes up, they will ask what I know about it! This causes more embarrassment than if someone just straight up asks me what my background is (a far nicer question than where I'm from..."no, where are you originally from? No, well, where did your parents come from then?" Ugh, how rude! As if being born in Carlton isn't a good enough explanation for my existence for them to decide if I'm worthy!). It is also confusing when I mention my sister who now lives in NZ - I now recognise the knowing nod and that it will be later followed up with "so how long have you been here", so I have to explain that my sister married a kiwi and that we're not kiwi.
So, it's the constant explanations that your DS might have to incorporate into his life and his interactions with people
I love what this bit of diversity in me has brought to my life - inherent acceptance and appreciation of 'difference'