So when ten-year-old Zoe Pemberton put her grandmother up for auction, she was brutally honest.
Among the many points listed were 'annoying and moaning a lot', although she admitted 61-year-old Marian Goodall could be 'very cuddly and loves word searches'.
Making her point: Zoe Pemberton put her grandmother Marian Goodall up for sale on eBay. In the background is the image seen by prospective buyers
It was, of course, only meant as a joke. But that didn't stop dozens of people placing bids that reached more than £20,000 before the auction was shut down for breaching 'strict sales policies'.
The sale began on Sunday, when Mrs Goodall was feeling down in the dumps after returning from hospital in pain following treatment to a knee injury.
Zoe was apparently feeling a bit annoyed at being constantly asked 'to do things like make her a drink' and decided to do something to cheer both of them up.
Her father Thomas Pemberton, 31, who cares for his disabled mother at their home in Clacton, Essex, said: 'I could hear Zoe asking mum lots of questions about her favourite drinks, food and height but I had no idea what she was doing.
'She called me over, pressed the confirm button, and said, "I've put Nan on eBay". I couldn't believe it. I had no idea she knew how to do it. She had even got a picture of my mum.
'Zoe didn't want to sell her nan but wanted someone to come here and look after her. It was really quite sweet. I didn't tell her off and it certainly brought a smile to my mum's face.'
Withdrawn: Mrs Goodall was removed from eBay which does not allow humans to be listed - but only after attracting bids of over £20,000
Describing the motivation for the sale, Zoe said: 'She was annoying me. She was moaning at me. I was on the laptop and suddenly thought I'd put her on eBay.
'I didn't know how much we'd get for her, maybe 99p.'
Mr Pemberton, a single father, added: 'We've had loads of inquiries asking if mum comes with a guarantee or MoT.
'Within a day there were £1,000 bids. Then it went £2,000. I couldn't believe it. Then when I last checked it was £20,541. I was amazed but my mum wasn't. She said she was worth millions.'
Mrs Goodall, a widow who has five children and 12 grandchildren, added: 'I just went along with it really.'
The auction was halted by eBay on Tuesday. Spokesman Jenny Thomas joked: 'While no doubt Mrs Goodall would have fetched a princely sum, eBay does not allow the listing of any human being on the site.'