Did the contractor explain everything in detail from start to finish? Was the explanation clear and was a written contract that explained the same provided?
Were you told how long the job would take?
Were you provided names and addresses of previous work?
Were you told what materials would be used on your home?
Was your phone call promptly returned?
Was the contractor on time for the estimate? This may be an indicator of how your job will go.
Did the contractor ask for money down? This should always be a red flag, at least for the residential repaints. Reputable painting contractors have charge accounts and cash flow to cover payroll and overhead.
Note:(When a job is extremely large, one that takes weeks to complete, it is common to request money during the course of the contract. This should be within a contract payment clause).
Is the contractor licensed and insured? Hiring an underinsured and unlicensed contractor leaves you with little recourse and you could be liable for physical injuries sustained on your property.