I Got drunk and blew my hard earned wages.
I got drunk and blew my hard earned pay.
In both cases what he blew was his hard earned singular.
It's rather grey area, I s'pose. A lot depends on whether you consider that there is an actual difference between "wage" and "wages."
I'm rather inclined to think that the plural form refers to the fact that they are a regular payment over a period, e.g.,
"The wages for this job are £200 per week."
as opposed to a reference to one week's pay, which could be couched as,
"My wage was right down to £180 this week."
However, I will agree that I have often heard the plural form used in the second instance.
As to grammar being subservient to meaning, I would only agree to that in cases where the use of "bad" rather than "good" grammar enhances the meaning.
I could never condone the use of bad grammar just because its use doesn't affect the meaning.
