To know bitters is to be marked by them. Many bitters are colored artificially or with caramel. I'm not too upset about this because those fake colors prove that the cocktail I ordered, actually contains the prescribed bitters. I am a fan of the airport Manhattan— if I see a bottle of bitters, I know that the worst think that can happen is just the need to strain some fruit flies out of the vermouth. Flies, though indicative of oxidized vermouth, are acceptable when you are on a redeye flight.
I painted this bottle to remind me of the countless neckties and buttondowns that have been marked by bitters. And, because income streams, you can get a Bitter Stain t-shirt here.