I have heard alot of that keep your hunting dog outside nonsense. Keeping a dog in the house will not ruin his/her nose anymore than being in a pen outside where smells are stronger-trash burning, skunk spray, etc.
I have a German shorthair who I will put up against any outside dog in a hunt test. He lives for one reason - to please me... and it's because of the bond we formed from him always being with me. He is a couch dog until the orange and shotgun come out then he is all hunt.