Sometimes I buy basics from George at Asda like t-shirts or socks, or Tesco for the cashmere when it's on offer. You can buy online now, so I only buy when they are on sale as queuing to pay separately can take a while and mixing it with groceries at self-checkout can annoying when someone has to remove a tag. In the US, I shop at Target for sportswear as they carry branded goods and always have sales on too. I wouldn't buy an outfit, but for basics like socks they carry a good range and quire cheaply.
I do sometimes, especially when they are on sale. They are not really high quality, so I just buy clothes that I will wear at home. There are days when underwear are on sale, so I buy those.