I forgot the mascarpone yesterday, so it sat in my bag in the living room for half a day and the night, instead of in the fridge.
The question is, of course, is it still ok to use? It looks fine, of course, or I wouldn't be asking.
Cheese is a cultured product, so you should follow the advice in the question:
Since it's been acidified and (if it's store bought) probably also pasteurized, it's very unlikely that any harmful bacteria would be able to compete with the "good" bacteria. Most cheese never go bad in this way - they just go sour, rancid and/or grow mold.
Which means that if it looks fine and smells fine and tastes fine, it should still be safe to eat.
Cheese is essentially preserved milk; it was originally intended to be stored at room temperature (before refrigeration existed), it just keeps its quality longer in the fridge.