I have not had a problem to date with suppliers and was not aware of these side issues though it is better to be prepared / forewarned. Hate it when you get sideswiped when you are the last to know.
Unfortunately it seems that the industry does tend to attract shady types from time to time - perhaps its a hold over from the days of cash based machines and people guarding routes etc, or maybe its the same in every industry, and we're just more aware as its out hobby. Fortunately forums like outs help to some extent to enable people to see both sides.