Hmm sheep , i had this and it has been my only complaint since starting wfp.
went to a house about 8am and cleaned his windows, left by 8.30am then got a call later saying his windows were poo,
went and had a look and he was right, found out after that the builders came round about 8.45am and started cutting slabs, hence cr@p all over the glass before it had dried, i didnt charge and now another cleaner does them trad,
oh well win some lose some
Haydn