Do you think shopping at charity shops is an 'ethical' consumption? Why/ why not?

Do you have any favourite charity shops? (Yes, mine is Oxfam!)
I'm currently conducting a dissertation research about consumption of second-hand clothes at charity shops.
People around me gave me some opinions about the question, including...
-YES because the part of money I spend goes to poor people in Africa
-NO because charity shops sell those fast fashion brands and by buying those clothes, consumers are reproducing the whole evil system of clothing industry

So, what do YOU think? It would be most helpful if you could give me some opinions with a bit of your charity shopping experience :)