Not in my experience, With age comes maturity and they generally are comfortable with what they are offering.
But as for being dirty, I think that's down to an individual. I once briefly dated a nurse (18) who was the dirtiest woman I have ever met, The second time we shagged she stuck some balls on a string up my ass and pulled them out as I was coming. It was the most amazing orgasm ever but naturally I followed through... I was mortified at what I had just done, she on the other hand loved it and started smearing it all over her... She would be mid 40s now and I don't know how she could have got and dirtier than when she as 18!