I typically use them on arrival after a red-eye - either the arrival lounge at LHR if I have a work day ahead in London, or coming off a TLV - New York redeye with another connection to somewhere else in the USA or in some place like FRA after coming off a redeye from the USA before getting on my flight to TLV. It's refreshing, a good way to get over the jet lag, and nice to be clean.