I can totally identify with Ladylust on this!
Each and every time my phone rings with a name and location ( meaning I have met them already at their home/hotel ) I have to quickly struggle to recall ANYTHING about them before I pick up - even if it was the same week. I usually fail and just blag it.
I know that I am happy to see them again or I would have marked OID/NW! after their name ( Only If Desperate/No Way! ) and if it has been a fabulous booking they get * or ** too!
If I have the time I dig out my 'little black book' to read up a little info about them, as I think it is a nice touch to ask about their poorly parrot etc

but I am usually too busy getting ready and rushing off to bother.
This happens in my 'real life' too. I have lost count of the number of times I have conversations with people in the street/shops/gym and then treat them like a complete stranger and ignore them the next time we pass

There are also huge blocks of my life that I simply seem to totally forget. I used to keep a full-on diary and it is mind-blowing to read sometimes.
The up side of all this is that most negative stuff is simply on default delete and every day is brand spanking new to me! X