I did buy a hand knit sweater (unfortunatley not of the Aran style) of natural unwashed wool when I was in Ireland touring 5 years ago, and it was rough with small bits of what looked like bark or wood, smelled of lanolin, and felt a bit greasy and heavier than expected. One good woolite washing later all but the rough bits were gone, and even they were less noticeable, the color of the sweater lightened a bit from that natural dirty tan, and the whole sweater felt lighter after drying thoroughly. And the leftover wash water was significantly discolored from whatever came out of the sweater. Must assume this type of wool is what you are remembering.

None of my Arans were knit of anything this raw or rough.