Dave, he was a newbie

and the 2 oldbies (Keith & I) didnt have them either.

Dave, on that carpet having or not having overshoes would not make much difference I assure you (I normally wear crocs inside the house/flat).
I took photos of the carpet before the clean but photos didnt show up the spills too well at all.
In parts it was quite bad, and as I said the agent was thinking of fitting new carpet but asked me to go along and see if it was worth a clean. Not the worse I have cleaned but it was bad enough.