I received a reality check the first time I took a big load of old clothes to a charity second-hand shop.
When I packed the bag I had been careful to pick only items that were washed and not stained or torn or overly worn.
I handed the bag over to a rather harried and grumpy volunteer and she asked me to stay while she sorted it.
I was put out at first, thinking she was being a bit ungrateful - I could be selling those clothes on Trade Me instead of donating them.
But then the sorting began and her reject pile grew.
Most of the stuff that was cheap to start with didn't make the cut. Wouldn't sell. Of the rest, anything with more than the subtlest sign of wear was not acceptable for the same reason. Winter coats? No thanks, it's summer and there's no room in storage.
With the choicest items were selected, I was sent off to find a clothing bin - or a rubbish bin - for the rest.
I felt bad, both for taking the volunteer's time and for having misjudged the acceptable standard.
Now, an attempted do-gooder with a slightly different idea of what makes a secondhand bargain is one thing, but ditching stacks of disgusting and clearly unsellable goods at these shops is quite another.
Yet that is the kind of carelessness some volunteers at secondhand stores in the Bay of Plenty - and no doubt around the rest of New Zealand too - face on up to a daily basis, as we reported this week.
Mouldy sofas, stained mattresses, ripped furniture, broken barbeques, and - I can't believe I'm writing this - items covered in urine or poo have been among donations.
In some cases, the goods were tampered with or rained on after they were left on the doorstep outside of business hours, but the original dumper still holds some responsibility for that in my eyes.
And it's not just stores being hit. In Pāpāmoa, a community food swap stall closed due to all the worthless non-food rubbish left around it, and I've seen the same situation at clothing bins.
This is costing charities money better spent on their community work, and wasting the precious time of their volunteers.
It's easy to rail against this obviously bad behaviour, but that doesn't change much.
Is catching and penalising perpetrators an option? It would seem unlikely given the resources that would be involved, the "donation" grey area and the petty nature of the act.
Unaffordable dump fees are often cited as one reason people resort to this.
Perhaps some sort of concession system for people in financial strife would incentivise some dumpers to do the right thing.