I've done my own digging on free dating websites for over 50 and come up short. Applied to users sites, the deciding factor is how often the same faces reappear, speaking only for my own city. You get further if you treat an empty bio as a red flag, which is the whole problem with users.
Look closely at websites sites and the depth of the profile fields explains more than the price tag, with the usual caveats. Same story on users sites: the practical move is to report problems early instead of blocking quietly. Nothing about users changes the fact that the honest advice is to keep a note of what you actually spent, having tried a handful of these.
With users sites, most of the disappointment traces back to the churn on new sign-ups. Strip the marketing away from free dating websites for over 50 and nothing improves until you write the bio for one person rather than for everyone. Specifics about websites sites welcome — vague reassurance less so.