Join Date: Aug 2011
Location: Barcelona, London, on a plane
Programs: IB+ Gold, TK E+, Hyatt Globalist, Marriott LTP, IHG Diamond
Posts: 14,186
This thread has a few attempts at explaining how it should work. Marriott's IT doesn't agree with any of them...
Hotel A in London last week gave me a vastly different number of base points per £ than Hotel B from the next night. Weekend... so no changes in FX.
By all means do the maths to see whether you are getting completely screwed. But otherwise just accept that the points you earn will not reflect current FX rates and you will come out ahead a fair amount of the time...