To stay on the topic, I have noticed the same thing while wearing Black Watch after dark at the zoo during the "Lights before Christmas" event. Since the majority of the lighting is in the trees, ground level was fairly dark and I'm sure that the tartan was nearly all black to those who did see me.

My Edzell might have been a better choice as it is a lighter color than either Black Watch or National Fallen Firefighter Foundation (NFFF) tartans. for reference, NFFF is black based while Rocky's (USA Kilts) Firefighters Memorial is red based.

Only two gents approached me about my kilt; both were interested as to where I had purchased it.