I always advocate the importance of telling someone when something is problematic - but in a nice way (at least in the first - or second - instance) so that they are given the benefit of the doubt. For example, "I may have misunderstood the situation, but I felt that your comment on my appearance was unwarrented." However, I do sometimes fall into the trap of "ignore it the first time" (hence "second instance").
It's sometimes ok to ignore a comment which you believe you may have misread, at least the first time...it might well have been you. Also, it may be such a little thing that you may not feel it needs made more of. However, if it happens again then something needs to be said. I suggest this, not because you were affected by it, but because there is also the chance that the person who commited the behaviour did not realise they were doing anything wrong. At this early stage it is easy to "nip it in the bud" whilst it's barely an issue. At this early stage it's also best to go with a comment in the style of paragraph one.
Recently a number of people have been talking to be about situations which have involved the "no response" response.
The first was someone who felt that there was some inappropriate behaviour from a colleague but believed that by not responding it would signal disapproval.
The second was a recruitment manager who was "ghosted" by a candidate - they wouldn't return calls nor answer emails.
To spend a moment on the term "ghosting" - for those of my age group - I believe it is when someone you may have been expecting to call you doesn't call, and in fact ignores you...so treating you as if you were a ghost. (Or is it they behave as if they were the ghost!? I'm sure someone can set me straight...but either way - it's again a lack of response, and again, to some extent, signalling disapproval.)
However, in both cases let's look at the reaction of the person on the reciving end - they either don't know they have done anything wrong, and they may continue to push with the behaviour (thus escalating it) to try and get a response, or merely continue with a bad behaviour which no-one has told them to stop.
Yes, no response is a response, but it's not a very professional one (and this is true whether it is deliberate or due to disorganisation). Neither is it a helpful one to you if you want anything to change.
Isn't it worse waiting and hoping (in both cases) than dealing with the fall out immediately? If you prefer the slow burn to the ripping of the band-aid, maybe you'd disagree with me, but with so many things to fill my mind with, I don't want to have to worry about "you" as well.
Some tips to respond assertively:
1. Try to respond calmly offering the benefit of the doubt in the first instance eg "It may be my interpretation but..."
2. Explain the exact problem behaviour ideally with an example, and say why it is a problem for you.
3. Explain what your hopes are in the future for that interpersonal communication.
Secret tip 4: Remember your value! You deserve to be treated professionally/with respect and there is no reason to settle for less...but also, when you have addressed it politely, leave it - at least a while - to give it time to change. (You don't want to become the over-responder either!)