I think that there are just so many reasons to hide your face and not many not to. Some punters will complain they want to see your face but most of them are not that interested in paying for your services they are just being nosey so on top of stopping family,friends,co-workers if you have another job etc seeing your face on these adds you also stop nosey people looking at your ads and recognising you.
If you market yourself right and have some decent shot of yourself then blurring all or part of your face won't affect your business. Punters probably select more on body shots than face shots and on how you market yourself in your ad.