Many of the decisions made regarding flooring, in terms of what buyers will prefer to see, will be market specific. Often the price-point of the house will dictate the extent of upgrades required for flooring.
Updates and Repairs
Replace worn, stained, or outdated carpet
Stretch and tack down loose carpet
Check grout for condition, and re-grout cracked or recessed grout (clean stained or discoloured grout)
Touch-up minor floor scratches
Refinish worn hardwood
Upgrade as necessary