I hired this person because he was listed on Angie's List. This man claimed he took and passed his contractor's license test after he signed me up for a project (Feb.) that included fixing cracks, painting, repairing a gate, installing a screen door, etc. He said he would charge me the original "handyman" prices. He postponed the start date, brought one worker who fixed a few cracks, repainted the gate terribly, but ruined a dining room ceiling when his worker used silicone in a tube instead of the expansion tape, spray ceiling covering, and paint I had purchased saying this silicone was "better". Then they said they would have to paint the whole ceiling and charge extra. They left holes in the walls and did a sloppy paint job in several places. I just paid them to get them out of my home as I felt intimidated as a senior citizen who is handicapped. I will try to have the main guy come back when I let him know what I need redone. Don't know if he will come back without charging me more.
I did go with the highest bidder and it did not matter. They did a shoddy job and threatened to take me to court when I pointed out mistakes that they made based on their work standards stated on the quote. I have not paid them yet, just filed a complaint with the BBB. No money down asked, no contract signed. The boss stated I have to high of expectations just because I live in a 121 year old house!
We had a bad experience with an interior painter years ago, with the crux of the problem being him overcharging us at the end for "extra work" he didn't anticipate. One thing I'd strongly recommend is making sure it's in the contract that any additional work or growth work is estimated and communicated to the owner as soon as it is identified, otherwise the owner is not liable to pay it at the end.
Oh, where to begin? Let me start with 'watered down paint'. 25-50% before the material gets to the site? Impossible. You would basically be painting with water at that point. It would be less of a hassle, and cost, to simply use proper material. You would be forced to apply three coats instead of two, as the coverage would be horrible. Whatever cost you think might be saved in materials would be lost in labor.