You should not worry too much about the droopy look with red eyes as most giant dogs develop such a look including Bullmastiffs, English Mastiffs and even Bloodhounds. Since dogs have 3 eyelids, they have their own mechanics of protecting from dust and mites.
Consult your vet, if there is a red clot-like spot in the eye or excessive discharge. Some discharge is acceptable in such breeds.
Hope this helps :).