Yes I agree, but I had been caught out by the sodium vapor lights at BKK airport. It's 4 AM and paid a 300 Baht taxi fare I dragged out of my wallet, the driver looked at me strangely but said nothing. Was later I discovered I had stuffed the 1000 note given to me by my hotel (key deposit) amongst the 100s and they look much alike in the lighting especially if one is in a hurry.
Lesson Learnt!