Problem with HP printer and Laptop.

Just bought a new print cartridge at Staples and it works good. I asked the girl there if this was a common problem and she said sometimes the refills work or will work for a while then stop, sometimes the printer can't read the refill cartridge. I cleaned the thing off good with a paper towel and I could not see anything around the front where the printer is suppose to read the cartridge. Apparently the ink may coagulate some also where it comes out causing this problem. I guess it is new cartridges from now on.