I generally don’t buy clothes online, and as such normally always check it fits properly before purchasing. So I rarely have to return anything, if I do I have no qualms in taking stuff back for a few quid.
Also I don’t tend to buy that much stuff, so again rarely have anything to return.
However at this exact moment I’m about to order some kitchen wall tiles and floor tiles ready for my builder. We’re going to over order just in case, and any unopened packets will be going back.