I guess its one of those without a correct answer.
On the one hand a pax can prove a distraction to you, are you going to complete the checks as thoroughly,
on the other, you might do an even better job, particularly if you are tring to impress your pax how diligent you are
,
and on the third hand, you mgiht find some of the questions your pax asks makes you think about why you are doing certain checks,
and of course finally, if your pax is a nervous sort, pointing out all the things that might not be working could well only add to their alarm, in which case they will be a complete nervous wreck by the time you take them flying.
Me, well just tell them you are counting the engines to ensure the number agree with what the check list says. They usually think you are joking, so keep a serious face, and tell them it is important becasue you lost one a few weeks ago.