Unfortunately, there are plenty of cases where a painter has stolen items from a home or caused damage to the house or injury to the homeowner. Subcontractors may not be as skilled as employees, and the contractor you're hiring may not have much experience working with them, making them more of a risk. Additionally, ask if the painters are employees or subcontractors, and what the screening or hiring process is like.
Start by thoroughly examining the outside of the house or outbuilding -- not just the exterior walls but under the eaves, around windows and doors, and along the foundation. Look for split shingles and siding, popped nails, peeling or blistering paint, mildew, and rust stains. Once you've identified the areas that need attention, roll up your sleeves and make the repairs.