Take incredibly misjudged punts on journeyman players who have very briefly shone .......................Why take a dodgy punt?
A 'punt' which costs nothing - or next to nothing - isn't really a punt at all.
If the player turns out to be quite happy having made more than enough money to keep him in comfort for the rest of his life, fine, tell him to sling his hook. If, on the other hand, he has realised how his actions (regardless whether they were legal or moral or not) have ruined his reputation as a footballer, and he wants to achieve some of the things he was expected to achieve as a teenager he might be worth having. Let the manager have a look and decide.
Giving him a trial costs next to nothing and involves no commitment.