hmmm wow thats odd, i always always put mascara on my bottom lashes too. but Mine never smudges.
when does it smudge is it like a few minutes after you've put it on or is it hours ? 'cause if its minutes maybe your mascara just takes a while to set, if so try not to let you bottom lashes touch you skin for a while, you could do this by putting your head down and only your eyes looking up, this way you can look in the mirror too. and if its even better apply the mascara this way. :)
or i suppoze you could get some different mascara, or even water-proof mascara. !