You should be doing your inspections after you are under contract. That is the natural order of things and it keeps both of you from wasting each other's time. If the condition is going to affect the price, have the seller tell you what the exact condition is with a realistic price assigned to each home. Then, during diligence, do your walk through with the seller. If the home is not in that condition, then you have him there to point it out. At the end of the walk through, you can talk about a price concession face to face if it is warranted.
If you are trying to remain secret about it through the inspections (most tenants are smart enough to know what's happening) then you can pose as a maintenance man, appraiser, banker, insurance rep, etc.