I used to have an Epson printer and used aftermarket inks - whilst the ink itself was okay (colour wise etc) I did have issues with them blocking the printer head up, drying up much quicker then OEM inks - the shop that I bought them from eventually had to flush the printer for me to try to clear the blockages (did FOC for me) and since, I have only used OEM inks in any printer I have...
Was this on an Epson 3880 series