CARB HEAT - When OK *NOT* to use?

[AvFlyGuy]

After a flight around the local patch when I put it back in the hangar, I took a good look around and the carb was almost drippy damp. This was on an 80* day with 40-50% humidity. I know and have experienced a near engine failure due to carb ice, but was able to catch it in time to apply heat and felt really lucky.

What atmospheric conditions do NOT support the need for carb heat on landing or op's below 1700 or so RPM??

Or does one just use it every time, no matter how hot it is outside?

 

[captual]