Once I was doing working in a street when a lady asked me to do her house too. Nothing unusual.
I did the house a few times, but the lady, who must've been about 30, got progressively weirder every time I went. Then one time she absolutely insisted that I hadn't done the top ones properly, and seemed quite distressed about it. So, against my better judgement and because I didnt want to be nasty, I did them again.
She was still not satisfied, and nearly in tears. I was at a bit of a loss at what to do. I told her not to worry, and to go into the front bedroom and watch while I did them so she could be absolutely sure. (By this time I was having doubts about her sanity, and really didnt want to upset her anymore!)
Did them again for the 3rd time.
She said that was ok now and paid. "weird" I thought.
Next time, I had second thoughts about doing them, but as I was at another house she walked past and waved so I had to.
As I went in through the gate, she had placed a large (football-sized) block of chalk on some silver foil on one gatepost, and an equally large lump of coal on some silver foil on the other gate post. "Too weird, Last time I do this house" I thought.
I did the house, trying to ignore the fact that all the furniture inside had been thrown around and looked like the result of a burgalry. She paid and I left.
A customer across the street said it would be best not to call at her house anymore, as she had some "problems". Apparently she was a witch, and had woke the whole neighbourhood up at midnight the week before by running around in the street screaming at nothing.
I didn't go back!
[PS I have since learned that the Chalk and Coal thing at the gateposts is a witches sign, so if you see that anywhere, be careful]