I would have to say if it is something that is already worrying you. With reference to your beard affecting services offered etc.
Then yes, simply mention it to the SP on first contact.
Then again we all know the limitations regarding translation and understanding with some WG's.
You might get one or two thinking your asking if they have stubble
It has only happened to me once, where a SP has told me no RO because I had not shaved that morning. She was actually very hot. But because I got a little narked with her attitude, I walked.
But in all my punting years. I have been clean shaven, stubbly, goaty and full beard as the mood takes me.
never had any problems per'say.