Call me a pedant but...

...Is it really OK to use the word 'poorly' as an adjective?

I might, with the soundest of grammar say
That house is poorly constructed.
Considered on an hourly basis I may be poorly paid, but in some of those hours, I get to sleep!

But can I really and truly say:

His stomach has been poorly.

Poorly what? Poorly ventilated? Poorly exposed? It's an adverb, dammit! Yet for the past few nights, I have heard seemingly well educated people say sentences very similar to the above.

So how is it that this little adverb has come to be so sorely misued?