Was a little bored today so I decided to try some different search terms on SA. Results were interesting, enlightening and in some cases disturbing.
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Try them for yourself and post your experience. Leave other filters wide open. Some yield fairly predictable results, others are... well find out for yourself, please.  
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Pregnant
Nut (look for Freida48 near LA, but be ready!)  
Twin or Twins or Sister or Sisters (the plural forms make a difference)  
Platonic
DD, or LG, or some form of DD-LG
Performance  
Set the age filter to 50+ (keep a still drink nearby!)  
Dominate or domination
Submit or submissive
Anal
Pervert
Oral
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Feel free to suggest other interesting terms.

and it can be amusing as to what pops up.  Although, I was surprised as to the number of girls who check Other for ethnicity.

I like to try :
polyamorous
cunt
fuck

Good callouts!  Polyamorous (or just poly) is a good one. It could be interesting to see how often poly appears on profiles with "married but looking" or "open relationship".