I made a job board scraper when I was looking for work. I found job listings from at least 6 years prior. I replied to some of them to call them on their stale listings. Not surprisingly no response. The lack of oversight or quality control is annoying, so make your own
Many places post job ads, but they don't really look for anyone, they just need CVs in case they'll need someone in the future. Waste of time.
One place laid everyone off, in the job hunt after that I found job ads from the same company, for my own role, for enough less than I earned that the ad had to have been many years out of date.
As everyone was laid off, nobody inside to contact. Messaged the (by this point former) CTO on LinkedIn, was a surprise to him too.