On my other forum, we have a current spate of fake applications. Most of them just seem to be automated things that fail to complete the process, so they aren't able to do anything. Occasionally, one does become active, these give at least the impression of being real people, as they make a good effort at posting plausible things. They are, however still easily identified as 'fake', as they post things that are intended to look like an interaction, but without any real content.
One of them was posting every few days, without any direct contravention, not even coming back to edit in a link to a post, after it had seemed 'clean', etc. So, I let him waste his time.
But, then he made a mistake that I wasn't prepared to let lie, so I removed him straight away.
A couple of weeks ago, he posted in an old thread about plumbing issues, in an effort to make himself look real - but, he claimed to have recently used a forum member who was a plumber, although he never posted much. He found that strategy by reading a few earlier posts in the thread. That was his mistake, as I know that the reason that the plumber hasn't posted much lately is that he died five years ago.
The plumber's widow still pops on now and then and has just been on, in fact, but all trace of the errant spammer is long gone now.
It's not necessarily a victimless crime...