When did I notice something wrong?

I'm trying to pinpoint when I noticed something wrong.

Five and a half years ago, there was an article in the paper saying that conmen were going around visiting old people and telling them their roof needed repairs. They offered to have a look and do minor repairs for $50, then they'd come down from the roof and say there were more holes in it than they expected, and ask for $200 and the amount would keep creeping up. In fact all they were doing was climbing around on the roof and getting paid.

These conmen visited my mother. She made a big fuss of them because they said they were unemployed and looking for work. She made them a cup of tea and fed them. They climbed around on her roof. They made holes in the garage roof by climbing on it and it leaked forever after. They told her they could fix her roof for $800. They took her to the bank and she withdrew the money. They then got the hose and hosed down the roof. That's all they did. She thought they were wonderful even when I told her they were con-men. She denied they were. She said her roof now looked 'beautiful' and was all fixed up. I wanted to call the police, but she got very angry and said they were good workmen and she'd disown me if I did anything like that. So there was nothing I could do.

Five years ago, Mum decided to sell her house and move closer to me. She put her house up for sale with an estate agent. The price was $430,000, with a $30,000 negotiation built in. $400,000 was the going rate for houses in her area.

Unfortunately a con-woman went to see Mum without the estate agent and told her lies. She said she desperately needed the house for her sister, who needed three bedrooms for her children. She asked if Mum would accept $300,000 as that was all she had. Mum agreed and lost $100,000. I was angry and devastated. I told her off, but she said to me "It is better to accept a lower offer from someone who comes with their chequebook than to wait for a higher price." She didn't understand that she was meant to let the agent do the negotiating. She didn't accept that she had been conned, even when the buyer put up a large 'For Lease' sign as soon as the sale was completed.

So I suppose Mum was around 78 years old when her judgment started to go.