I would honestly worry about a grooming shop that would not allow an owner to stay..however I always advise owners that it's actually less stressful for the dog if the owner leaves.
I think people tend to give dogs human emotions, and it's just not the case. At the end of the day dogs are dogs and should be treated "like a dog". Most behavior problems animals have are from owners treating them like humans.
A human child is much different and a child would probably freak out if the mom left him with a hairstylist unattended.
I don't have a problem with owners watching..because I'm not going to hurt someones dog regardless if they are or are not there. I would like to feel that the owner has some trust and confidence in me and I would be lying if I said I felt slightly offended everytime i'm asked by a client if they can stay... I tell them "as long as you don't talk, look directly at or stand right in front of me". I've had owners sit there and make baby talk noises while i'm grooming the dog and sent the dog home half-done. It's irritating.
Marian: I'm just ranting, i'm sure you are not like that and probably just feel more comfortable. Perhaps someday give your groomer the benefit of a doubt and just ask them if the dog acts better once you leave. As long as "mom" is there to save the dog they usually act up. Once mom is gone though a dog calms down almost instantly and "gives up" realizing mom isn't there to save them.
To answer your question: It's not difficult to do face/feet/tail, it can be very difficult your first time though..not because of what's being done but from nerves. I was so nervous the first time I took clippers anywhere NEAR a dogs face. I had visions of the clippers going in the eye and blood going everywhere, i imagined every single horrible thing that could happen...and not once has it ever happened!
It's very difficult to do something like shaving the face when you are nervous. You could get a little micro trimmer like what AgilityIG uses on her dog Vinnie..her dogs face/feet/tail always looks great and she does it weekly I believe.
A GOOD pair of clippers will cost 120-150 and can sometimes be found much less on craigslist or groomers.net in the swap and shop section. I bought my first set of everything used for a great price!
Anyway..sorry for the long rant. I do understand why people like you want to stay with your dog. Unfortunately there are a lot of BAD GROOMERS out there! There are people I would not leave my dog with for a SECOND and i've worked with most of those people at Petco! Of course I worked an a really awful Petco... I have since met fantastic groomers at that store..one of my best friends is still a groomer at a different Petco..so it just depends on the place. Some of the big chain stores actually have decent groomers adn good training. I just happened to work in a really crappy place!
I wish you luck! I think learning to do some grooming yourself can be wonderful bonding experience with you and your dog..just make sure to only do what you are comfortable with, watch videos, and learn everything you can before actually doing it.