Stamps With Clipped Corners

I have been noticing a few classic u.s .stamps and some beer revenue stamps with clipped corners. Was there a defined purpose for this treatment?

i have one for sale at the moment and when I first got it, I was wondering the same thing!
was it just trimmed for looks or did the postie at the counter just have time to do it?

I think they're done as mischief by collectors. Postal clerks wouldn't bother, wouldn't have the time, usually. It looks nicer to some and you get rid of any corner fault at the same time. So who did the deed to British Guiana Scott #13?

These were always around, of course. What we are seeing are ebay sellers scraping the bottom of the barrel in all areas of stamp collecting. Going through ebay's offerings of US machine flag cancel covers, for example, there are some good full clear cancels but usually on really damaged, yellowed/browned covers, typically at ridiculous prices. The proof of that is that they only rarely sell, re-run over and over. These are the ones rejected by the hardcore collectors in the past, often because they could find better ones. So where are those? Did they all get so badly stored that they ended up as dreck? Are they still locked up collections or dealer stocks? It's not bad images I'm talking about here -- these are faulty items that would have been ignored or passed along in large lots in the past, now presented as items worthy of $$. Not to me.

Mischief and eliminating damaged or rounded corners sound quite plausible.

To blather on, around 1900 and earlier, a lot of collectors were the casual type and not students of philately. So they could also cut stamp designs to shape and perhaps just save them in a little box, along with labels, stationery cut squares, anything paper with a design. I'm guessing again that the stamps and stationery were later thought to be of value and were saved with a lot of the rest thrown out.

I was gifted some years ago by distant relatives with commems from their country. It was their own little collection in a stockbook, all stamps from the P.O.; they knew enough to store them properly. In it were a few where someone had cut away the outer parts with denomination, etc. and saved the artwork only. So it continues.