I  am not sure what it is AMP .. may be I should not at all to participate  in this thread ... seems as here gentleman asking if it is ok to negotiate... I think and  true gentlemen and all ladies : would know the answer on that ...
 as to if it worth added costs .  
 let me do analogy ..
- of course every of you gentlemen booked hotel at some point of life and you possibly well we'll well know .. how 200  more updating  the room.. ..
 and we talking about room :
- if it is clean ?-
-If it is not stinky-  
-If there is luxury in interior..  
 if bed are comfortable  and no bed bags..
 etc..
 and it is about room .... too sad to point it  out .. but it is how and with rest things we do buy ...  
as if you will buy cheap snickers .. they may be even would not comfortable for your feet to wear them and an hour ..
 It is same with everything.
So costs added always gave you value added.
I think always . am I wrong ?? ladies and gentlemen?  
it is still January .. I be back this week Wednesday in states . there still no snow??  and I did changed wheel on my car on winter wheels .

I was asking specifically about Asian massage parlors in NYC, which is particularly interesting to me since the parlors all provide fairly standardized services and routines at identical cost, which begs the question of whether additional services are commonly negotiated with the ladies working there.

There is no deeper meaning.  All it means is sex is an option.  If you think GFE means any specific list of acronyms, or any mental attitude, well, not at a MP.

For most of the AMP's or KMP's that indicate GFE service for certain girls, it means DFK and BBBJ is included for an extra fee.
Sometimes 2 pops.
Seems like this is the only difference from the normal service.  
I dont think he is asking about the normal massage parlors that charge a door fee then you negoiate extras with the girl