Can't help with how to clean them, but if you get anymore as soon as you get them get some cling film and stretch tightly across the top smoothing it well just down round the sides and then using a very sharp knife run round the outside a couple of mm from the top and remove the excess.
You really can't see it once it's done and it stops the dust getting in to them in the first place.
Some I have kept the plastic bit on after I realised bits stuck and those little flies eeeuuuugh. Maybe I should use them for what they are for and burn them :-)
Be careful if you do burn jelly candles, I know they say don't leave candles unattended but that goes doubly so for jelly candles, and don't burn them for more than about an hour at time.
Oh and the cling film way of keeping them clean was adapted from the old practical joke when you do it to a glass and then watch somebody try to pour themselves a glass of water... oh the joy was never ending in the school canteen :)
Try the cling film on the loo under the toilet seat - stretch it tight & it is invisible - just a huge puddle on the floor!! a rotten trick for your worst enemy !!!!!