I fail to see the left side type of argument

Who wouldn’t

If I start pronouncing them, can I get your number?

For sure? I don’t think it’s likely there’ll be a way. You can only get best guesses.

In my case it’s mostly intuitive, a sort of uncanny valley but for listening that clues me in that something’s off, and then I start looking for stuff actively. If the “band” has many different genres or varied styles, if I go to older videos and the singing is different or the voice is altogether a completely different one, if there’s no social media presence, if there’s no interaction with the comments, if the account’s relatively new, if there’s no sense of improvement in a natural human way (as in they clearly got better at playing), etc.

But nothing will ever be enough for me to be 100% sure unless it’s extremely evident.