Its a natural reaction for victims and media in reaction to a fraud being committed, is to spread the warning message to prevent other victims. I often even do it myself, but the truth is that warnings don't really work that well for a number of reasons, after-all if they did then fraud would have been stopped long ago!
Firstly the chances are that any particular warning will be completely irrelevant to you, you won't happen to meet they guy selling shares in the pub or doing deals on cheap air purifiers or use the ATM with a skimmer.
Secondly too many warnings, there are warnings about every aspect of life thrust upon us constantly, we simply cannot absorb them all.
Thirdly even if the warning is relevant to you then it may well difficult to recall that particular warning in the required circumstance and warning tend to be general and not specific. Even if they were specific about say certain phrases, then fraudsters would simply change the phrases.
Rather than warnings, perhaps a better approach is to build review/fraud checks into processes. I think the most important rule would be to involve someone else in decisions, but, it must not be to ask their opinion on something, so not "Should I do something" questions, but more specific questions like "Do you think these people are who they say they are" or "Do you think that these people can deliver these products?".