Now, that means different things to different people. To me, GFE means lots of kissing and she'll probably give you a BBBJ, but this isn't always the case. It's more of an attitude where she makes you believe she's into you.  

No GFE would be more of the cold mechanical "let's get's this done" type of service with no kissing.  

Solo mis dos centavos.

However when you see "nonGFE" in an ad, you can generally conclude that provider does not kiss and does not do BBBJ.  
If a provider advertises she IS GFE, you can't tell what that really means. It does not necessarily mean she does do DFK and BBBJ. Some people consider GFE included certain services provided. Others say it's about attitude and personality. The best way to determine a provider's service and attitude are reviews and backchannel info, not by an acronym in an ad.

... FS and non-FS.  But as others said, there's no one definition of GFE.  Or non-GFE.  You need to do your research to find out what THIS provider means.

it means whatever the provider decides it means for her.  As my esteemed colleagues above have said, there are varying degrees of what is involved.  I do agree that if she is non-GFE, there is probably no DFK, or maybe kissing at all.

I don't look for GFE, I look for my 2 deal-breakers.  If there is no DFK or BBBJ, I don't see her.  Simple as that.

LLAP,
Swim

and to others; GFE is an attitude.. not a checklist.