I started shopping with Thredup over a year ago and have had so many bad experiences that I'm done. On 5 separate occasions now, I've ordered things that were described "like new" with no damage, but then they show up with very obvious stains, or large holes in them where the seam has come apart, or the matching belt that's supposed to come with the item (and was pictured with it on the site) is missing. Each time, I contacted customer service and nothing was resolved. They are very rude and not helpful in the slightest.
I also sent a bag of clothes to them, and like many other people have mentioned, they only paid a tiny fraction of what they ended up selling my clothes for. I sent in high-end items, many of which still had tags on, and the bag was packed completely full. They sent me about $18. I could have easily made over $100 by going to the local consignment shop. Seriously, don't waste your time or your money. They're a total joke.