Not so hot also is a way of saying that you do not really like something.

VOA: special.2009.12.06

I of course picked the wrong day to wear a sweatshirt under really hot lights so thankfully I came prepared with another item from the-- from the store.

当然，我在主光灯下穿了件运动衫，这确实不太明智,幸好我过来时,从商店准备了另一件。

哈佛公开课 - 计算机科学课程节选