@Alex Kolbo Bring your agent if you have one! It's difficult for them to represent you and advise you if they have not seen the home.
You should ask the seller to tour of the property so you can accurately determine how much your rehab cost might take so you can pin your numbers down! The home may be in better or even worse condition than you expect which can drastically skew your numbers. If the seller hem haw's around because the property has tenants, they may not want the tenants to know they are considering a sale. We have offered for our buyer to wear a tool belt and act like an inspector or contractor and walk the property with the seller.
Additionally, you could write the contract contingent upon a personal visual inspection and approval of the property as part of your due diligence. In our area, we make an inspection part of the contract, however in other areas you could bring an inspector with you when you tour the property (if you go this route, let the seller know you are bringing your inspector as it make take more time and they will look much deeper than a typical walk-thru), or the contract may give you a window of opportunity after writing the contract to have any and all inspections with a opportunity to get out if you don't like what you find. Good luck!