But that's always a risk with any property I guess isn't it? And there's legal recourse if the clutter isn't cleared.
My stepdad was a giant dickhead when they sold their property and unbeknownst to us, left a load of stuff in the shed that he thought would be "helpful" to the buyers. (he was previously a keen gardener and the buyers had said they couldn't wait to have a garden - he was moving to somewhere with no garden). Their solicitor contacted my stepdad's solicitor the next day giving him 24 hours to get it cleared or else he'd be charged £500-1000 for the buyers to hire people to come in and clear it!
I was utterly mortified as I was the one who had done all the communicating with the estate agent for them. Stepdad had assured us that the garden was empty - when we helped them on moving day, we just took his word and didn't check the shed!!! Even now, more than one year on, I'm cringing just remembering this....!!! So, so embarrassing.
I definitely wouldn't rule out a house on the basis that they MIGHT leave behind some of their clutter.