Every week, millions of plastic bags - wrapped in yet more plastic! - are delivered to UK households (unrequested,) requesting that we fill them with clothes etc to be collected for the benefit of various charities.  I personally receive 2 or 3 of these PER WEEK. 

Aside from the fact that the collection companies are commercial businesses that donate pitiful percentages of the value of the goods collected to the stated charity (which is not obvious unless you read the small print,) the volume of single-use plastic involved in the manufacture and packaging of these collection bags must be huge. 

Unlike single-use carrier bags - whose use has sharply diminished over the last few years - there is a further problem with these collection bags:  many of them are never used for their intended purpose and possibly finish up in landfill.  This is due partly to the frequency with which the bags are delivered and partly due to the recipients' reticence to use them due to the commercial nature of the collections and the risk of theft.  

Whilst I understand that not everyone can get to a charity shop and that (even if the value derived is small,) charities appreciate any support that might otherwise be lost, there must be a more sustainable solution.  One idea might be the delivery of labels that householders could attach to their own bag IF they decide to leave something out for collection, but I'm sure there are others.  

Incidentally, there is a code of conduct that states that bags must not be delivered to any home displaying a notice saying that they don't wish to receive them - but how many people know that and how many distributors even bother to look for the sign?