5 stars

I bought a set of these when they first came out in 2000 I believe. I too had trouble with the foam sleeves that came with them.
A little ingenuity will probably solve your problem though.

Go out and buy a pack of cheap foam ear plugs.(like the ones you get for $1 in the little bag at a race or something) You can usually find them [...] in the sporting goods section. They come in packs of six pair and are typically orange, pink, or some other bright annoying color.

Remove the sleeves that came with the headphones and cut a pair of the foam ear plugs to match their length.(or the length of the headphone tubes)

The tricky part is making a hole through these plugs in order to make sleves out of them. I used a large paper clip that I straightened out. You should hold it with pliers, tongs or some type of metal tool.(so you don't burn yourself) Heat the paper clip with a lighter or stove burner until hot enough to melt a hole straight through the middle of the plugs that you have cut down to size. When the plugs are cool, place on the headphones and use them as you would the factory sleeves. If you mess up, just start with a new set of plugs from the pack. Even if you use the entire pack to get a good set, it will be worth the improvement. You may want to go ahead a make a spare set ahead of time as they do get dirty and eventually wear out or begin to get hard.

It should now be easier to get them into your ears as these foam plugs don't expand as quickly. You will also notice better sound isolation and better sound quality over all.

1 stars

In theory, these earbuds should be great -- they are supposed to fit in your ear canals just like those foam earplugs. However, this foam does not stay compressed long enough to get it into your ear correctly. Then, after struggling to get it in correctly for several minutes, they end up falling out as soon as you start to sweat. Save your money and buy a better quality earbud.

5 stars

I have worn earplugs to bed for a few years now, so maybe that's why I found them so easy to adapt to, but I've tried just about every kind of ear-only headphones and they never work. These stay in your ears and sound great. For this price, you can not go wrong.

5 stars

Even though this is my 2nd pair, these are def the best headphones I ever bought. When used as directed (shrinking the foam between your fingers, pulling down on your ear lobe, then quickly putting the buds in your ear and allowing them to expand) these headphones are only rivaled by a few. The highs are cool. The mids are good. But the bass, OMG the bass is excellent! I have owned many headphones over the years and these are the only ones that have strong and clear bass. I haven't even mentioned the noise cancellation. As I said, when used as directed, not only will you not hear anything in the gym, these are the only headphones I can use on airplanes to drown out the engines. If you refuse to pay over[Price]for headphones like me, these buds are definitely for you.

4 stars

These phones are lovely. I was skeptical about buying them because of the mixed reviews from people who hated these phones, but they rock! They stay in my ear because of the earplug design and have lovely bass. I wasn't expecting electronic noise cancellation because the description said nothing about it, but they do a pretty good job on their own. If you don't mind the tiny bit lesser quality than electronic noise cancelers for a good price, these are the phones to get. The only thing I wonder about is is the cord really 4 feet long? It seems a but short...Oh well :P
Anyway, to make a long story short, totally worth the 15$ (In a good way :])

4 stars

The sound quality of these buds is excellent as everyone else has noted, and the nature of the foam material does a good job of cutting outside noise out as well (as a daily bus rider).

I was intrigued by the low end frequency response (10Hz) for such a low price, and it certainly does a good job of meeting it. To feel the full bass effect, these buds need to be inserted properly deep into your canal, or it'll just sound tinny.

There have been mixed reviews with the fitting. As someone with very small ear canals, I was hesitant, but with enough trial and error I learned how to get these puppies to fit properly. Don't be so quick to assume they just don't fit you, it takes some learning and there's no real reason why the form-fitting foamies won't fit anyone really.

A good tip I would offer is: keep the foam bits clean and wash them with soap every so often! When they're dirty, they tend to have less "grip" to stay in your ear properly (this is especially important for the small-eared). I know Koss sells other interchangeable foam/rubber pieces that may be an even better fit for other small-eared folk, although I haven't tried this myself yet.

My problem is the cord. Right from the start it seemed fairly thin and delicate, it tangled often because of its rubbery texture, and two months later now, it has finally pinched at the plug causing the right bud's sound to cut in and out. Luckily, it's a very simple DIY repair and I will continue using these buds for the sound quality, but it's still a shame it happened so quickly to begin with.

(FYI, Target doesn't ship the purple ones pictured anymore. The new generation of Koss's "The Plug" is black all over; much slicker looking.)

5 stars

i could rattle on for hours how amazing these are i just opened them and started listening to kanye west and theres nothing betta.the bass is so amazing!!!! i recomend these to anyone who has the money.these are no doubt the best ive eva had

4 stars

Can't beat the price but they most certainly are a short term item (6 months - year max) I am about to purchase my 3rd pair because you just cant beat the price for the sound quality they deliver. Another thing, they do offer lifetime warrenty but you have to ship back the defective and include 8 bucks for return shipping.

2 stars

...before they go out on you, if not sooner. Yes, they sound great, yes, they form fit the inside of your ear while blocking out noise, yes, they are highly affordable, and yes, you get the bang for your buck.

BUT

They tend to go out on you. It always starts with the right ear bud first. You get the crackling, then the sound in, sound out, then eventually, dead silence. Yes, you will try to move the cord around, only to get more crackling then pfft! Done.

Short-term wise, they are a marvel. Long-term, shop around more. I've gone through 6 pairs myself. Why do I keep buying them? Hey, I'm not a long-term kinda guy.