"She is as red as a tomato."
The problem of this sentence is that it's very vague. It could mean her face, or her dress, or her self (whatever the hell that means). Without any context, it can be very ambiguous (though my gut feeling leans toward face).
In actual usage, I would personally add some sort of qualifier (e.g. her face, her dress, her shoes, her t-shirt, etc.) to the sentence to eliminate the ambiguity.
I am guessing that there is something odd about the usage of that paticular counter.