Answer
Almost every warning sign shows up before any work starts.
Painting has a low barrier to entry, and after storms the Houston area sees a reliable wave of operators who will not be here next season.
Get more than one written quote. Ask for the insurance certificate. Check recent local work. Pay on a schedule tied to progress, never entirely up front. Keep everything in writing, including changes agreed once work has started.
See how to choose a painting contractor and why insurance matters.
A reasonable one for materials on a scheduled job, yes. Being asked for most of the total before work starts is the single most common warning sign.
Ask for an insurance certificate, recent local references and a written scope. All three are easy for a legitimate contractor and awkward for anyone else.
Written, itemised, insurance provided up front. Free and no obligation.