IMO, Scarf Darmanitan and Scarf Chandelure work extremely differently. Darmanitan is about trying to rape one pokemon and hoping they don't protect. Scarf Chandelure is about messing with the opponent, since Chandelure has a variety of viable sets. Also, Scarf Chandelure is an equal opportunity ass kicker, since STAB Heat Wave hurts like a bitch, while Darmanitan has what, Rock Slide? Just saying that they work very differently.
Also Krookodile and Landorus make very good scarfers. Both of them are discouraged by their meh speed, which can hold back there abilities. By running Scarf, you can beat a couple of notable threats, like Scarf Chandelure and Hidden Power Ice Thundurus. Scarf Landorus is particular can be very useful, and I've stated my thoughts about it in my analysis. While I can't speak on the behalf of Scarf Krookodile, I do know that there's someone in the forum who has some experience with it. (I'm not saying who because they might intend on using it) So they can speak up if they want to.
While Scarf Haxorus is a common pokemon, it's really not that good. It's just kind of outclassed by Scarf Darmanitan in it's job, dealing as much damage as possible.
Edit: I almost forgot about one of the best scarfers in the metagame, Vaniluxe. Yes, the Ice Cream pokemon is good. Why is that you ask? Good Special Attack and Blizzard, which is always good in doubles. But wait, there's more. Did you know that Ice hits around 1/3 of the metagame supereffectively according to the most recent stats? Add in hail and you get a 100% accuracy double targeting move with great power, coverage, and a 30% chance to freeze, arguably the most annoying hax ever.