First of all, use of a gun should be a last resort.
Second, how do you determine who is "shady"?
Third of all, if someone is "shady" but not really interested in you, you just showed you have a gun. Now you are a challenge. Now he and six of his buddies are going to drop a cinder block on your head first and take your gun and wallet.
The only time a gun should be revealed (Unless one just enjoys showing off that they have a gun) is in preparation to using it.
Drawing a weapon should be the last resort before firing it.
So far I have had to present the weapon several times. Never needed to go any further, but in those cases where the gun was drawn, if I had not had a gun, the situation would have become very bad for me.
Oh, and the cinder block thing: Have an old guy I know who is a tow truck driver and buys and hauls away junk cars, often in pretty bad neighborhoods. Usually has thousands of dollars in his pockets. Is well known to keep a loaded revolver in his coveralls pocket and another one under the seat of his truck. He is the type that is always brandishing his gun or implying he will use it. Not a real nice guy IMHO. He is well known in the neighborhoods.
One day three teenagers were where he was stopped checking an address before turning into an alley. They crushed his skull with a brick through the open window of his truck and robbed him of his cash and both guns and he was hospitalized for months.
Two of them were caught thanks to witnesses and from what I hear from a PD who was involved one of the reasons for doing it was because this white guy had been in their neighborhood for years acting all high and mighty because he had a gun and well, they showed him.