I would argue Joe is one.....I mean it's simple english

Joe takes professional photographs, therefore, surely, he's a professional photographer?
G.
Who or what determines what 'professional' actually stands for in this case?
Is there a body or committee who vets this work?
Technically good?
Artistically good?
One is quantifiable, the other isn't - an image can be technically good, i.e. correctly exposed and in-focus whilst being of poor artistic quality; badly composed, uninteresting etc etc
It can also be of poor technical quality whilst being artistically good.
Photography, just like any other visual medium is interpretive. I may like something that others dont.
If you are going to apply the appelation 'Professsional' to photography or a photographer, it must be wholly concerned with the business aspects, rather than the artisitic, which are open to subjective differences.
Therefore I think it is correct to say that someone could act in a Professional manner, whilst at the same time producing technically poor work by standards agreed upon my a majority of other practicioners in the same field.
The converse is also true: an unprofessional photographer could produce stunning works...
It's one of the reasons I've recently stopped using the word 'amateur' in my posts, preferring the word 'hobbyist' to describe anyone who doesn't now or doesn't intent in future to make photography their main earner.
Amateur denotes a lacking of ability, whereas hobbyist does not.
I think we should also try and find a new definition for the other end of the scale.
I think being a 'good' photographer is enough...whether a pay cheque is part of the equation or not has no relation to the quality of material produced.