When official voices for a charity or a cause ask for stuff, you can give stuff. Give what they request, only what they request, and in good condition. Don't give unwashed or unfolded clothes. Don't give expired or open food. Don't dump and run.
Give money. Give time. Give votes. And if you know they want your stuff, give stuff.
After Hurricane Katrina, waterlogged schools full of developing mold were inundated with donations -- of textbooks from the 1960s, torn paperbacks nobody wanted, and old national geographics. Then it became their problem to throw away someone else's unwanted stuff.
Don't make suffering people the solution to your problems about not wanting to throw unusable clothes in the trash. Don't make them the repository of your helpless survivor's guilt.
From The Guardian's liveblog of Grenfell Tower aftermath:
He added: “I haven’t seen this much aid out of a war zone, but the council just hasn’t stepped in. There is too much in the way of donations. But the problem is how to get it to the right people, and what you do with the surplus. One man, I’m sure with the best of intention, left a massive box full of milk - and now volunteers have to figure out what to do with a box of gone-off milk.”
From twitter user pastelchalk:
She turned up in Range Rover 4x4 & gave over a bag of bedsheets. I check them just to make sure & the bed sheets had blood stains on them— Eleanor* not a demon (@pastelchalk) June 15, 2017
Just because someone has lost absolutely everything doesn't mean you can give them the absolute dregs of your consumptive waste!— Eleanor* not a demon (@pastelchalk) June 15, 2017
We feel bad throwing things away. Find a charity that actively wants your things, or suck it up. We feel bad being okay when disasters happen. Go volunteer to help, or become an activist for those trying to prevent similar tragedies, or write a check, or suck it up. The best of intentions and a fiver will buy you a cup of coffee.