One of my few and worst Jamaican vendor experiences was on my first visits to Jamaica. I was travelling on a mini bus out of Ocho Rios bus park with a Jamaican female friend, We had to wait a little untill the bus filled up so I reckoned to just chill and buy a beer and juice from one of the many vendors, The beer was HOT as in not cold at all. I said to the vendor that I didnt want it,
A huge drama ensued, Where many people joined in on the incident I took the good advice of my Jamaican friend and paid up and shut up.
it was my own niave mistake for not testing/feeling the tempeature of the bottle by holding it before the vendor had opened it. Plus once the beer was opened the vendor could not sell it to another customer . I bit my tongue paid the price and learned from my little mistake,
If I fancy a cold beer I always handle it to see if it is the one for me.
Cold and nice Red Stripe.

I have only ever had one or two bad experiences with vendors.