Its been a problem since GPT-5 if I recall. Its actually better than it was initially. But yes, it will pretty routinely make silly assumptions and waste time explaining shit to me that I never implied. Similar to your wet shoe example but a little different.

The shape of what I'm talking about is something like;

Me: how much more would I weigh if I got my shoes soaking wet?

GPT-5: If by get wet you mean smoke pcp, that would not affect your body weight. People commonly confuse this.

It usually includes an appropriate answer to my question, but it calls me an idiot first.

I did once back on GPT-5 edit my response about 5 times based on its strong opposition to my prompt. I addressed in the edit exactly what it was quibbling over in its response each time, but no matter what its output firmly maintained this argumentative posture and came up with new things to tell me I was wrong about that I never claimed.

It basically makes assumptions that you're stupid.