I had a long thoughtful response written out this morning and then my connection timed out.
In a nutshell: I think for consignment and resale to be worth it, you have to enjoy the process, otherwise it is just a burden and a chore with very little return. It also seems that regional differences matter a lot. Urban areas with higher volume seem to be more discriminating about what they take in, but rural areas probably have less variety to choose from which makes using one's store credits less interesting. I'm really lucky in that I've managed to find consignment venues that align with my lifestyle and preferences. I don't really have many clothes that would be suitable for Dress For Success type orgs.
To be honest, consigning at the gear shop feels like a good solution. When I was a student and just getting into outdoor activities, having a place where I could go and find high quality used gear at cheap prices was SUCH a boon; I really appreciated the things I found there. So I consign my stuff and imagine young folks with little disposable income coming in and finding just the right thing for their next adventure.
Not many of my clothes go the rag route; we cloth-diapered DS, so I have what feels like a lifetime supply of car-cleaning and floor-cleaning rags. Thank goodness for municipal textile recycling.
Also -- I tried ThredUp once and I agree the cash you get back is so dismal it's hardly worth the effort. I have a Poshmark account but find buyers and sellers there much less professional/courteous than on eBay, so eBay remains my preference for online sales.
I haven't yet amassed enough housewares to need to donate them. In fact, I'm very grateful to all of you who do take unwanted housewares to the thrift store because that's where most of my dishes, flatware, candleholders, vases, etc come from! I'm a big mid-century modern fan so I love scrounging for Canoe Muffin silverware and Fiesta dishes.
Our Humane Society actually turns away sheets and towels because they receive more than they can store. I'm just in awe of people who have extra towels to begin with. Our relatives have learned to bring their own when they come to visit .
Okay, I guess I re-wrote my long response!