Charity shop bosses have urged people to stop donating "patently unsellable" items, as they are deluged by mountains of bags from spring cleans.
The Charity Retail Association (CRA) has warned the public to avoid dropping off "disgusting or really badly broken" pieces to their local shop, as they end up having to be thrown away.
Its warning comes amid an influx of donations, believed to be the result of many Britons spending lockdowns decluttering their homes.
Robin Osterley, the chief executive of the CRA, said: "This isn't anything terribly new - charity shops have always had some donations which people can't use. Our message to the public is be thoughtful about the sorts of things you're donating. If it's something which can be sold, that you'd want to see in a charity shop, then do by all means bring it along.
"If, on the other hand, it's disgusting or really badly broken, then think of disposing of it because shops are there to make money for their parents charities. They're not household waste sites.
"We don't want to give the impression that we're not grateful for people bringing their stuff in - we really, really are. Since lockdown, we've tried to be a little more assertive about this because our members are likely getting very large numbers of donations.
"Having to sort through donations which are patently unsellable is obviously unfortunate for them and in some cases quite unpleasant actually."
He also warned the public not to leave piles of bin bags in doorways, adding: "It's unhygienic, it's very unlikely to last the night with animals and the weather, and it might get nicked. It's actually fly tipping. People really shouldn't do that. Please bring it into the shop."
Among the worst donations reported by charities include a soiled child's potty, boots with concrete on the soles, chipped glasses, teapots without lids, and ripped or paint-stained clothes. Hospiscare, based in Devon, said it faced an annual bill of £32,000 to dispose of donated items it cannot sell.
It estimates that around 20 per cent of donations can be sold, while 60 per cent is recycled and 20 per cent has to be thrown away.
"It's not just about donations being preloved, it's also so they are ready to be loved by somebody else," said Helen Hutter, the charity's retail manager.
"If you wouldn't buy it please could you dispose of it in your own bin. We all want to work together and make more money for our patients and that has to be a great thing."
Cancer Research UK, Oxfam and Sue Ryder this week warned those keen to drop off unwanted items to ring up their local shop instead of turning up unannounced with bags of goods.
Tom Richardson, head of retail operations at Oxfam, said: "People may have spent time during lockdown decluttering, so our team of dedicated volunteers are looking forward to accepting generous donations. As always, we are looking for things like good quality, clean clothing, books and homewares."