126.825 - Does mode S show you the speed we are commanding the aircraft to fly or does it show you the actual IAS? As previously mentioned someone winding back the speed in the window does not mean that they will not be 160kts at 4d, it does however mean that the thrust levers stay shut and the speed bleeds off naturally without early use of the gear. The autothrottle gets a bit keen to add thrust on my type and the speed control with initial stages of flap can be pretty poor, with a commanded speed of 160 you could be indicating anything up to and extra 10-12kts.
Another point made earlier is that for guys not to 'second guess' what you want then positive speed control needs to be issued on every approach. Before I get jumped on I would say it is on 95% of approaches but factor in bad weather, missed calls, busy frequency (even a slightly overloaded controller!) and occasionally you never get the reduction (typically from 220 to 180) but as you are hitting the glide at 7d you get 160 to 4, an immediate 60kt reduction in 3 miles! Even maui in his big shiny triple will struggle from there - especially as he won't have already reduced and will be strictly complying with you last instruction!
Finally this morning (126.825) we got '220kts if not already' when downwind, again this sort of implies that you expect us to reduce around the usual gates if the frequency is busy.