The thread below has got me curious. I often drink half a cup of coffee and nuke the remainder. When I was in an apartment without a microwave, I'd balance the mister coffee pot on the stove and reheat (boil) what was left, often dumping in my unfinished cup, cream and all. I can stretch a whole week or two on one pot. I'm not picky about it being "fresh", "day old", etc. - I could never tell the difference, and was drinking instant until a year ago.
However, a few people have pointed out that reheating the CREAM might be problematic. Usually I'm using that powdered fake stuff; if I run out, I might splash in some milk. Skim, usually, simply because that's what I have kicking around.
I've never noticed any ill-effects, but am I poisoning myself? I figure whatever dangers week-old cream or creamer might pose are offset by all that nuking.
Coffee afficianados need not reply - I'd like to hear from people who can get past my using instant and reheating it for a week or more in the first place! It's just the CREAM I'm asking about.