In a conversation with a friend, he slipped that he intended to go to an interview for a senior position in software development. I was surprised, since I was under the impression he liked his current job. Imagine my surprise, when after asking him if he wants to leave his job, he said he doesn't intend to. He would only go to an interview to test his skills and get the feedback (albeit only Boolean) about whether he'd get hired for a certain position, though he doesn't really think of accepting an offer from the said company.
On the one hand, I realize this is some very valuable information for a professional.
On the other hand, I have the feeling it's highly unethical and basically it is wasting the time of the interviewer, since I doubt he'd take something from the interview.
How is that regarded in the industry? Is it considered rude and unethical? Or am I in the wrong side in this argument?