Dash is like a windup rubberband driven toy. Cute but not useful for anything serious.
Me: "Hello Mr. Merchant. Would you like to use a payment system that is Instant, Secure, Doesn't rely on a third party charging you 3-5% in fees, and leaves all of the funds in YOUR control?"
Merchant: "No, those things sound terrible"
Somehow, I don't think that would be their answer.
You'd be surprised how common that answer is among merchants. Most merchants don't want to change their payment systems because they know the digital currency market is small. They have a working system that they're used to, taxes to account for (their system in most cases will be set up already) - why would they take on the risks of downtime, computer security & volatility?
Merchant adoption of Bitcoin is happening so slowly, not saying it's impossible for the same to happen with alt coins but it'll be a tough sell, especially in Dash's case because its main touted advantages over Bitcoin are more privacy & faster transactions. Right now Dash has either privacy or faster transactions, but not both. When merchants discover these kinds of dishonest marketing tactics it will be very difficult to restore Dash's reputation.