Lure burn out?
Poor set constuction, unclean equiptment, an area thats allready been trapped, etc.....are some of the reasons you get refusels and or a walkby, not from good quality lure.

If your using a proven lure, I don't care if your set was froze solid and a k9 came by, dug out the hole, licked his lips, pee himself, etc., he will be back when there is more lure down that hole, regaurdless if he's tasted/investigated it before.
Aslong as he didn't get snapped on the toenails when smelling that lure he will be back time & time again until caught.

Will a k9 avoid a smell that gave him a bad experience? Sure, short term....but come back 1 month later and you'll have 1 chance to get him again (especally after a rain fall, as they get dumb for whatever reason).......WILD k9's have a short memory and this is proven when you catch them with missing toe,etc. (not talking about fido here, that has been under our influence for many a year...you can't truly use fido as an example of how coyotes react as they arn't even close to the same)
I caught a late season female with a bad break in her left shoulder...I let her go....7 months later setting the same ground (not changeing a thing or the lure) I caught the same female again and know it was her when skinning left upper shoulder was healed, but basicly crippled and could see how the bone had repaired itself.....
So why would that female get caught in an exact d-hole with the same lure only 7 mths apart?
Must be a dumb one rite?

The only burn out that I know of is TRAPPER burn out....when one gets sloppy and or lazy.......its not the lures fault...look for another reason (someone beat you to the punch, your set constuction is unexceptable, your traps are dirt, you are dirty/sloppy,etc.).
A good lure is good year after year in the same area (unless you made him a smarty) but is only a temp. smarty.

You back down too quick Tim.