I've never been worried about anything I've posted anywhere.
Yes there are things on closed boards here (and elsewhere) that I'd rather weren't publicly available, but that's a different issue altogether.
Nothing I've ever been ashamed about, I'm always me and would hope 'me' is acceptable, whoever's reading.
Anyone whose posts anywhere are not
generally acceptable should probably be questioning whether they have some kind of problem.
But on that note, I'd hope that an 18-year-old's drunken selfie or random rude comment would not be held against them for anything; if in employment, then so long as they turn up on time, sober, and do their job, their free time should be their own to be 18
If, on the other hand, that 18-year-old spends their free time posting racist rants or 'muslims rule the world and everyone else must die' diatribes, they should realise not every prospective employer is going to be willing to offer them a job