Madoff fooled his investors, who lost their money. Before his spectacular fall,
Madoff generally enjoyed a good reputation among his clients and was also not singled out by regulators for more detailed review.
Can we really trust that a Government regulator approval stamp on e.g. financial institution guarantees true trustworthiness? Not really, you should do your homework regardless. It is a data point regardless, however, and better than no stamp at all.
Long-term track record is important. If an institution has been going on for 100 years, it lowers the counterparty risk, but then again you can get a rogue trader like
Nick Leeson in the ranks who brings down the institution (in this case Barings) overnight.

Personal reputation is maybe easier to gauge. I have used the metaphor of coloured pool balls to illustrate this.
If one holds a two-coloured pool ball in a hand so that you can only see part of the face, the observer can't really tell whether the ball is "solid" colour or a two-faced one.
However, when the ball is released from the grip, if you look at the side angle, you spot the two-facedness instantly.
This is what reputation does, it gives you are side glance on your negotiation partner. Somebody else can tell you if your negotiation partner is "solid" or not, when you cannot make that judgment with your own observations alone (since you have been drip-fed only the spotless facade).
Once you get your own observations married with the reputation feedback from your network, you got "
their number"!
Separating individual reputation from institutional reputation is difficult and another matter. However, I believe these correlate. If you have a good personal reputation, you don't want to work for shady firms. So I would recommend trusting individuals more than organisations as a loose rule. Just don't go too much along with your "
blink intuition"!