Should you throw out your old knee-hi's and pantyhose with runs? Gosh, no!
First of all, if your pantyhose has a run in only one leg you can salvage it for a while yet. Here is what you do: Cut off the offending leg and put the pantyhose back in your drawer. The next time you get a run in just one leg, do the same to that pair of hose. Now take the first one-legged pantyhose and put the leg of the second pair of pantyhose through the hole of the first pair. Now you have two good legs and saved yourself a trip to the store.
And DON'T throw away that leg that you cut off. You can still use the leg, or a knee-hi, with a run for your washing machine. Yes, I said your washing machine.
Once, just after buying a brand-new Maytag washing machine, I found that my clothes were still sopping wet after the spin cycle. I called for a repair man, who very kindly pointed out that the problem was that the sink, where the water drained, was clogged with lint (totally my fault and he didn't charge me for the visit - I love Maytag!). He suggested that I either buy "lint traps" (a little mesh bag that fits over the washing machine's hose) or use old hose.
I have found that a "ruined" knee-hi or pantyhose leg attached with a rubberband works just as well as the store-bought lint traps. And they are free!