Just got back from a few days on Vis Island, it's very beautiful but I found the locals quite unfriendly and, at times, hostile towards tourists.
No idea why this is, as I spent time in both Split and Hvar and didn't encounter the same attitudes.
In particular- avoid Bar Lembik by the harbour in Kut, the waiter there told me they had sold out of local beer and served me a Heineken instead -more expensive than local beer. Moments later he brought out local beers for his friends, when I questioned him about this he replied 'domestic beers are for domestic customers only'!
Also the staff at Ionios Travel agency were rude and unhelpful when I took the bike back that I'd hired for a day - after the brakes failed! After much argument they reluctantly agreed to give me 1/2 the money back.
The staff at Navigator travel agency were very helpful though and helped to arrange accommodation and boat trips.
I fully agree with the tip, but it's the Vis way, take or leave it. I was there several times recently. The service was friendly and I was able to order 'domestic' beer without any difficulty. Lambik is the best bar in Kut.
Is this your business?