I think the big magic thing here is consent and personal boundaries.
Like yes, I am a muscle and fat fetishist, I love the idea of being big and strong (and chonk). I have characters who are also the same. However, it doesn't instantly mean that I want to do vore, most inflation, or be pushed (or push) characters and fursonas to extreme obesity or musclebound levels. Also because some of my male characters and fursona look the part, it doesn't mean I want to be anyone's "daddy".
Those are just some issues that tend to make me uncomfortable and push me the wrong way. Another big issue would be how some people view my female characters, but that's inherently more complex than what could be answered in just the scope of bad roleplay experiences (although I did mention something about it earlier in this thread).
See, stuff like this is a legitimate thing people don't understand. You my good fellow, understand the golden rule of consent that most see and proceed anyways. I tip my hat to you in respect.