Seems like you work in a different environment. Here, our interviews begin with a coffee walk or inviting them for lunch; and no one has the attitude of “why the hell do you need to know what I ate”).
You can already see from the comments on this thread that there are strong opinions on both sides of this -- it's not a consensus. Flippant questions are a gamble is all I'm saying.
p.s. that said, if it were me, I'd treat it as a minor irritation and move on unless the candidate demonstrates a pattern of a lack of seriousness about the interview. It's one thing to be relaxed and casual, but not taking the interview seriously is not a good look.
Also if a company is extremely casual and everyone is in jeans and hoodies, ignore what I said in this entire thread. It doesn't apply.
This stuff really does work, I don’t really need it now because i generally find roles through my network.
Is any interviewer really going to tell you the politics are awful, or managers are overbearing? They'll probably give a typical non-answer like "the food is so good you can't help but put on weight".
Candidates do this also when asked their worst traits - it doesn't work.
When I'm interviewing someone and they ask this, I try to answer honestly, although I think it's human nature to still try to put a positive spin on it because a) I work here and there's some element of post purchase rationalization, for want of a better term and b) if they're a good candidate I want to sell them on working with us.
However there are forces in the other direction - it's not in my interest to deceive a candidate into a role that doesn't fit them if they're going to leave when they inevitably find out, or if they're going to be demotivated as a result. I have a vested interest in this being a good fit from both sides.
I also want to give candidates a great experience - we're a small company and not many people have heard of us. Word of mouth is the most powerful recruitment tool we have, in many respects.
To some extent this only works because I genuinely love the place I work and so the bad things I talk about genuinely aren't that bad (I would call them tradeoffs rather than things everyone would consider super negative).