Please note this.
Grills - Window grill, Door grill, etc.
Grilles - Speakers.
Yes, IMO, grilles do make difference in SQ. If the speakers are bright, forward sounding, these grilles do tend to tame the harshness to some extent, and yes i have noticed this in my speakers (MA RS6) with/without grilles.
Regarding cleaning, I use a soft cloth to dust the cones (very gentle) and the tweeter are grilled so can't reach them. There might be some right method to clean the cones, others might suggest i think.
Grille covers do affect sound quality and for serious listening they are taken of. All my speakers have been built without grills. I don't have any kids around the house who might poke the drivers though:yahoo:
you are lucky. i have 2 kids but i still have not designed the grills. with kids around, i think grills are useless as they have weapons like pencils , pens,spoons etc. the grills which protect speakers from these weapons will definitely affect SQ.
my speakers need armors rather than fancy clothes.:sad:
i understand you plight man - my daughter is just 7 months and she has taken a penchant for my surround speaker stands - if and when her attentions shifts to my hi-fi setup and components, i am in for trouble I guess.
Suprateep, if you have not already, please read the thread http://www.hifivision.com/speakers/3736-child-proofing-speakers.html. just for fun if not for anything else. You can also read post #39 to see if that method is applicable or is it too late.