You don't charge a "reasonable" amount--you charge the actual out-of-pocket costs (i.e. not for your own time, or the time of any employees of yours; rather, for vendors, contractors, materials, etc.) required to fix anything which exceeds normal wear and tear. Numerous holes in walls exceeds normal wear and tear; pet stains on carpet exceed normal wear and tear; etc. Find the actual cost to correct these issues--that's what you can charge.