We cruised 3 times with Carnival (brand new Liberty, Miracle, Glory) as we were cruising with 8 lines till last years.
Carnival was the only line we dropped completely. We did not see more drunks or parties than on other lines, it was not a problem. The ambiance wasn't there... too many tattoos , golden chains... We sailed on similar lines (pricewise ... NCL, MSC even RCI), and of course you meet some riff raffs everywhere (including HAL, Princess and Celebrity... do not remember on Cunard). But it is about overall numbers ... and activities, entertainment geared to them.
Latest ships - Mardi Gras, Celebration etc look interesting, but I do not feel an urge to book.