Second hand coop

Asking this question for a friend of mine up in Scotland.  She is thinking of getting some girls of her own and looking on Gumtree she has found a coop only a few months old......  Is there  anyway of telling if its redmite free??  I would hate her to get inherit problems.  If she gets it and cleans it with vandione or virkon giving it a good scrub would that be enough to deem it as clean from any bugs and illness??

Thanks

And if she does get it, make sure you tell her how TINY the red mite are! And that when they are not feeding off the chickens, they are grey/whiteish and even smaller than tiny!

Nasty things!   

mine was preloved too but scrubbed it out while wearing a very fetching bright yellow set off waterproof my oh gave me -i looked like captain birds eyes sidekick
then blasted it with poultry sheild in every nook and cranny inside and out then also duted for red mite ,done the run wood too just in case as im new too this wanted too make it all nice and clean for there arrival