I don't really mind the burn marks on several of my older chips, 1930's. I am lucky to have both burned and unburned of these chips. But some collectors are very picky and say that any type of burn is damage to the chip.
Way back in the day before ash trays it was common practice to rest ones smoke on a stack of chips. To me it adds a little character to the chip. Of course if the chip is really burned badly like the one in the scan I would consider it a wasted chip, but just a hint of burn makes for a bit of nostalgia. JMHO
Hava Happy