For example, they would compare every lease to the rent roll and notate discrepancies, walk every unit and notate age of appliances, carpet condition, any evidence of water intrusions etc.- As @Charles Carillo mentioned, you want to partner with someone who is going to keep you informed. 

We replaced carpets and repainted.

I'd probably just do more carpet and tile instead. 

Took one bathroom down to the studs, replace counter tops, carpet and painted.

REHAB BUDGET and SCOPE OF WORK : $90K ( built into loan) $30K for each Gutted unit$5K per existing unit x6 = $30K TOTAL Spend was $100K $4500 for Foundation issues, landscaping, etc 2 gutted units: new electric- 200 amp upgrade Blown insulation for attic ( r38)new sub floorNew insulation throughout New sheet rock ( 5/8 fire wall for exterior living room walls, kitchen and in stair well) New 6 panel doors throughout with all new satin nickel hardware New 6 panel Steel Front and Rear Entry Doors New plumbingNew HVAC system( all electric got rid of gas) New ThermostatNew lights New Hot water heater New kitchen layout ( removed half wall to open up to living room, built alcove for fridge to increase floor plan) New white shaker cabinets with hardware, countertops , fridge, stove, range hoodNew LVP throughout New Carpet in bedroomsNew bathrooms ( vanity, tub, enamel over steel tubs, tiled surround, vent fans, vanity lights, faucets, low flow toilets, shower heads, and actuators) Added 1 new window in each kitchenOther units: ( completed in 409 B and 407 D ) other units will be rehabbed once tenants move out New LVP in LR, BR, Kitchen and hallwayNew Carpet in BedroomsNew six panel doors/ hardwareGlazed existing tub/tileNew shower hardware Low flow water options ( toilets, shower heads, actuators throughout) New water heaters ( 407 D) Replaced AC 409 A ( it was 28 years old) New Fridge 409ANew Fridge 407CNew Stove 407 A Painted stairwells ( versatile grey) had attractive/durable commercial grade carpet installed on stairsInstalled new lights in stair well and motion sensors in 409 Installed Motion Sensor Flood lights on all the cornersInstalled Video Cameras on problem areasHad Duke Energy replace old lights with brighter LED on two poles Installed keypad entrance for both exterior stairwell entrances Cleaned/ repaired other AC units Fixed any issues with plumbing as neededFixed any issues with existing water heaters Installed new black shutters on both building Implemented quarterly Pest Protection Installed raised landscaped beds for 407 ( parking lot facing) Installed new Numbers for both buildingsPainted all exterior doors black installed new hardwarePainted central mailbox black We are still actively repositioning this property and will have another two tenants moving out end of this month ( September) but the property has generated enough profit from the other units at the increased rental rate that the business will be paying for these upcoming turns.

REHAB BUDGET and SCOPE OF WORK : $90K ( built into loan) $30K for each Gutted unit$5K per existing unit x6 = $30K TOTAL Spend was $100K $4500 for Foundation issues, landscaping, etc 2 gutted units: new electric- 200 amp upgrade Blown insulation for attic ( r38)new sub floorNew insulation throughout New sheet rock ( 5/8 fire wall for exterior living room walls, kitchen and in stair well) New 6 panel doors throughout with all new satin nickel hardware New 6 panel Steel Front and Rear Entry Doors New plumbingNew HVAC system( all electric got rid of gas) New ThermostatNew lights New Hot water heater New kitchen layout ( removed half wall to open up to living room, built alcove for fridge to increase floor plan) New white shaker cabinets with hardware, countertops , fridge, stove, range hoodNew LVP throughout New Carpet in bedroomsNew bathrooms ( vanity, tub, enamel over steel tubs, tiled surround, vent fans, vanity lights, faucets, low flow toilets, shower heads, and actuators) Added 1 new window in each kitchenOther units: ( completed in 409 B and 407 D ) other units will be rehabbed once tenants move out New LVP in LR, BR, Kitchen and hallwayNew Carpet in BedroomsNew six panel doors/ hardwareGlazed existing tub/tileNew shower hardware Low flow water options ( toilets, shower heads, actuators throughout) New water heaters ( 407 D) Replaced AC 409 A ( it was 28 years old) New Fridge 409ANew Fridge 407CNew Stove 407 A Painted stairwells ( versatile grey) had attractive/durable commercial grade carpet installed on stairsInstalled new lights in stair well and motion sensors in 409 Installed Motion Sensor Flood lights on all the cornersInstalled Video Cameras on problem areasHad Duke Energy replace old lights with brighter LED on two poles Installed keypad entrance for both exterior stairwell entrances Cleaned/ repaired other AC units Fixed any issues with plumbing as neededFixed any issues with existing water heaters Installed new black shutters on both building Implemented quarterly Pest Protection Installed raised landscaped beds for 407 ( parking lot facing) Installed new Numbers for both buildingsPainted all exterior doors black installed new hardwarePainted central mailbox black We are still actively repositioning this property and will have another two tenants moving out end of this month ( September) but the property has generated enough profit from the other units at the increased rental rate that the business will be paying for these upcoming turns.

I know the typical approach to replacing carpet is to prorate it based on life of carpet.

This is a moderately extensive flip, new kitchen, 2 new bathrooms, carpet replaced with laminate, wallpaper removed and either replaced or walls painted, and the works. 

In fact the Owners have made it really modern inside and for the last 33 years got it up to par with nice finishes newer carpeting comes with upgraded systems ,with a carport a fenced in yard and newer roof .

Carpet needs to be removed from 3 rooms and on stairs to the second level.