I think there is the BDSM definition of vanilla i.e. in no way BDSM ( and afaik they coined the phrase so that is the original def as it were)
And then the everyday common usage version. Where it means the less adventurous side of what most people think most people get up to.
Ok given the definition of vanilla mostly used here, (which is more vanilla = nothing kinky/bdsm) what do you call the other side of vanilla from kinky?
Because I have met lots of men who e.g. do not do oral, only really do missionary, view shaving as risque, will not masturbate in front of their dp, think their dp is out of order if they do, no sex during periods etc. Etc.
To them kinky is sex in the doggy position!
So other than deeply boring, what are they if not vanilla?
I would go for a scale of vanilla, normal, adventurous, kinky, really kinky, weird/specialist all of which are fine if consenting (and then there is illegal, wrong and nasty).