I don't have personal experience directly, per say, but I've heard much from several different sources who do know firsthand, and my verdict for whatever it's worth would be warm more than hot.
I also have heard many different personal takes so I tend to think that a person's individual normal body temperature affects how they think and how they perceive the temperature to be. Humans run an AVERAGE temperature of 98.6, but not everyone runs 98.6 exactly either. Some run a bit cooler, some run a bit warmer, some run right at the average mean temp. For instance, I personally run a normal temperature of 97.8 I get chilly easily and often. My ex wife ran at 99.5 and she wants the fucking window open in December because she is ALWAYS feeling hot.
I've heard dog cum described as warm, at the very least, and I've also known those who felt it almost as uncomfortably warm at times, the words "Almost scalding" have been used but I absolutely think that is a subjective and perceptive thing that varies from person to person based on running whatever body temp is normal for that person.
I do think warm is the best description in fact though.