I've seen a repetitive pattern of programmers dressing their resumes with technologies that they don't really know, but have merely touched on.
I always find attitudes toward resumes to be interesting. The entire reason we mention technologies on resumes is because we used them, and (assuming we're not completely desperate) we want to use them again. The mere fact that you have done anything in a language gives you a foot up on the person who truly has zero exposure to it. Experience is compounding, and each small step can be worth dramatically more than the last.
I've met too many people who believe that in order to list a technology on your resume, you must be an 'expert' in it, where the meaning of 'expert' varies wildly. These tend to be the same people who think that "evaluating a prospective hire," means, "find any point of weakness and exploit it." It's a weird, insecure defensiveness. A need to prove candidates wrong, rather than gaining an understanding of their skill set and experience.
A former coworker once caught someone whose claimed PostScript experience consisted of clicking "Print to File". I consider that nothing short of fraud. If a skill is on my résumé, I am offering to rent it to you for substantial money, which means at a minimum that I have already developed it to the point of being commercially useful. If there is no honest way for me to claim I've dabbled a little and I hope to be useless for less time than some others, it's because nobody has much reason to believe my uninformed self-assessment or care very much even when it's true.
That said, we once hired a guy who didn't know any Java (actually it was the same guy as above), because the interview made it perfectly obvious that given his intelligence and fluency in similar languages, picking up Java was not going to be a problem for him. He did not try to find an excuse to smuggle Java into his résumé, he was honest and let us make the call, and it worked out fine for both of us. If he had cram-studied Java and tried to pass himself off as experienced, we would have caught him being incompetent or dishonest or both, and that would have ended the interview.
A former coworker once caught someone whose claimed PostScript experience consisted of clicking "Print to File"
Was that deceit, or tremendous ignorance?
It seems to me that there's a huge problem with resumes and interviewing regarding unknown unknowns. 1-10 ratings, for example, vary wildly depending on how much you don't know that you don't know. When I graduated college, I was a 9/10 in C++. Now I'm about a 6, even though I'm ten times the C++ programmer that I was. :-) But I don't dare tell a recruiter that...
I do agree entirely with this statement of yours:
at a minimum that I have already developed it to the point of being commercially useful
Which is sort of my point. You can have employed a language or technology, professionally, to solve a problem, gaining very meaningful experience, without coming anywhere close to being an expert, or even meeting most people's requirements for 'knowing' something. I'm certainly not saying that people should list anything technology they can conceive, on the most tenuous bases they can rationalize.
I have seen resumes with 20 different languages. I simply email them to rate on a scale of 1 to 10, how good are you with each language. (So that I can have interview questions on their better language). Surprisingly (to me) or maybe not surprisingly, a lot of such people never get back to me on their ratings at all. It could be the same "weird, insecure defensiveness" you are talking about.
I can't speak for those people, but I might be put off by a request for 1-10 language ratings, rather than asking what my core skills are, or something about choosing technologies for a given problem. 1-10 ratings strike me as a bit like, "what are your weaknesses?"
I always find attitudes toward resumes to be interesting. The entire reason we mention technologies on resumes is because we used them, and (assuming we're not completely desperate) we want to use them again. The mere fact that you have done anything in a language gives you a foot up on the person who truly has zero exposure to it. Experience is compounding, and each small step can be worth dramatically more than the last.
I've met too many people who believe that in order to list a technology on your resume, you must be an 'expert' in it, where the meaning of 'expert' varies wildly. These tend to be the same people who think that "evaluating a prospective hire," means, "find any point of weakness and exploit it." It's a weird, insecure defensiveness. A need to prove candidates wrong, rather than gaining an understanding of their skill set and experience.