It states: Touch-Clean spray holes allow for easy removal of hard water build-up - but 
my photo shows brand new and one at least 7 years old.  No matter what I’ve tried I can’t get the faucet holes to look clean.  Maybe if I’d regularly scrubbed them with a toothbrush they wouldn’t have gotten like this??  Who knows?? Just recently started leaking so replaced cartridge- was still leaking so retightened the bonnet/screw nut (think it did the trick but we will see).  Haven’t had any other issues in the 7 plus years we’ve had it. Delta is very helpful if you contact them.