I realize that you are not referring to Anal, which already exists in the Services section.  
You probably want to know about anatomy, in the Appearance section.
Sure! TER can add this:
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Ass: [ ] Yes [ ] No

Exactly what is a fake ass?

I think those go one step beyond.

steatopygian.  (Google for more amazing pictures.)  
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But we do NOT need any more meaningless adjective descriptors.  If you want an ass category, there should be a panel of 6 or 10 silhouettes or images and let the reviewer pick the one that most closely matches the hostess with whom he met.  You can call it fat, flat, round, bulbous, balloon, bubble,  ... or steatopygian.  With a picture of the shapes right there, you don't need the words.  
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NO MORE ADJECTIVE DESCRIPTORS. USE IMAGES! As I have suggested for:
Body type (for build) using fashion or psychology silhouettes
Complexion color chart (rather than ethnicity) - Mattel or Pantone color chart
Hair color chart: pick the closest match
Etc.
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(Just like checkout cash registers are switching to icons and symbols so that staff can press a picture of a Big Mac instead of have to read the name on button or figure out the price.  A picture of a pickle means "add pickle." Etc.)

-- Modified on 1/26/2018 12:29:11 AM

"The real-life Popeye who injects himself with a potentially lethal cocktail of oil and ALCOHOL to grow fake biceps."  
http://satireandtheology.blogspot.com/2014/03/bodybuilders-via-oil-injections.html
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And MANY others. Google "bodybuilders oil injections"