Ink Cartridges

I suggest you disregard what your friend said. I think your paper might perhaps be to blame for a jam, but not your ink. Inkjet ink does not have anything at all to do with how the paper moves through the printer. The reason humidity might cause a paper jam is slight swelling of the paper especially cheaper uncoated copier grade paper. They happen sometimes. It might well be that your printer's rollers are clogged with minute particles of paper dust.

Some people say that after-market ink can clog or damage your printhead, but if you have been using it for 2-3 years, (Did you mean in the same printer?) I think you would have noticed streaks or missing colours by now.

I've always paid store prices for authentic ink cartridges and the trouble I have with them is that there is no way for me to see evidence/proof of the quantity of the ink in a new cartridge. I do little printing and by rights a new cartridge should last me for months, not weeks and when the cartridge is declared "empty" after a relatively short time, I have no alternative but to buy another new cartridge. I've got into the habit of putting a sticky label on the casing and writing the date of purchase, where I bought it and how much it cost, not that I can do anything about it because I can't, but it serves as a reminder of how often I get ripped off by ink cartridge manufacturers.
Over the coming couple of years I am anticipating that laser printers will become much cheaper. A black and white laser printer is already available for only $179 and I'm sure it won't be long before colour laser printers are within reach and the ink jet printers will become a thing of the past.
To add insult to injury, where new ink jet printers are concerned, there is very little ink in the cartridges that come supplied with a new printer. Quite recently a friend of mine bought a new printer and after only a couple of print outs there was no more ink. The replacement cartridges are very expensive, over $30. The printer was in the vicinity of $90. At the risk of over emphasizing too much, the death of the ink jet printer can't come too quickly, for me at least. I'm sure we will all be a lot better off in the end. Meantime I feel like we are being held to ransom. I HAVE to buy authentic ink cartridges because the nearest store for cheaper ones is over an hours drive away and I never buy anything off the internet because postage is far too expensive. However I have heard a rumour that a new store is opening up in town called "Cartridge World" that sells cheaper ink cartridges. I'm smiling.

Ink Cartridges
Contrex:
Thanks for your quick reply. What made the "non-conforming ink" argument so plausible was that my friend backed up the allegation of the salesman. At one time I wondered why there were so many sites that seemed to survive for years selling inkjet ink (I understand that much of it is reclaimed ink - which might be an environmental plus). It becomes difficult for me to pay $20-25 when I have been able to get excellent ink (and long-lasting cartridges) for $9.95 or lower.
And yes, it was the same printer (although it was the same printer that ultimately jammed). Thanks again. I think I'll go back to the internet for my printing supplies.

Ink Cartridges
Vonda 1941:
This is my lucky day! Two GREAT replies! Your point about the possibility of "short weight" is well taken - and the second such complaint I have heard. As I mentioned, I had been buying my ink from the internet, so it hasn't happened to me (although I have bought a few cartridges for earlier printers at the store).
Although I sympathise with your comparison with Laser printers, I feel that purchasers will have the same shorting problems. I can remember the old HP lasers where the cartridge was $75, and never seemed to last.
With regard to the "original" ink that comes with a new printer, the salespeople are now told to warn the customer that the initial cartridge is merely a "starter cartridge." Not so much for the customer's benefit as to get an additional sale of the store version for full price. A "double whammy" so to speak.
Thanks to Contrex and yourself, I think I'll leave the world of $25 ink cartridges that may be only half full, and return to the more commercially honest (NEVER thought I would ever say that!) world of the internet. Thanks again.