I really don't think that a rabid-Republican will thow hir shoe at Obama at this point - now anyone who does so is associated with al-Zaidi and that's presumably not an association ze would want, even if it does get the incident in the news. I guess only time will tell.

As for the last bit, good point :). In addition to the scuff mark issue, I would add that any position in which the soles of the feet are pointing at someone is likely to be considered immodest for women anyway. While I may choose to ignore that consideration at home, if traveling it seems prudent not to.