I can't speak for Canada as I'm in the UK but most vets I've come across
here genuinely care for the animals or they wouldn't do the job.

If you're suspicious of your current vet then the only suggestion I can
make is try another. Is your friend trained in feline dentistry..? If not
I would take what they say with a pinch of salt; personally I'd be more
inclined to trust the vet.

See what the dental specialist says.

Ivor

I'll tell you my experience, which is not exactly like yours but might
give you a slightly different perspective.  My cats have a good vet.  I
trust his skills.  But he is also in the business of selling products
and services.  He has been "gung-ho" on dental cleanings ever since his
practice began offering this service.  

He discovered that of my cats had two little pink spots that looked like
places where the gum extended slightly down onto the tooth.  These, said
the vet, were the feline version of cavities (don't recall the technical
name for them off the top of my head), and would require x-rays to
determine whether the teeth should be extracted. The teeth would
eventually become painful, he said, and it was merely a question of
whether they could be just "watched" or whether there was already
extensive damage.  He gave me some written info describing the
condition, and I also researched it on the web.  Sure enough, these
cavities do present as pink spots.  Since anesthesia was needed to do
the the X-rays, he said, and since my cat had a little tartar (only
Stage 1, but she was going to be "out" anyway) he would clean her teeth
at the same time.  Reasonable.

She went in and spent about 6 hours in a cage before it was her turn
with the tech who does the cleaning-- a specially trained person,
although I had not been told that the vet didn't do the work himself.  
Anyway, OK.  But this cat is one of those who objects dreadfully to
caging, riding in the car, being in unfamiliar environments, strange
animals, etc.  Well, I thought, sometimes you gotta do what you gotta
do.  So she spent the whole day there, had the anesthesia, had the
x-rays, had the cleaning.  The little pink places that looked like gum
tissue turned out to be gum tissue.  A hefty bill was paid for what
turned out to be nothing, but oh well.  It was hard on my cat, though.

When we got home, she pulled the fur away from the place where the
catheter he been inserted into her leg so that she could keep it nicely
licked.  Over the following weeks, she "over-groomed" that leg so that
the fur from knee to foot was mostly gone, then she started to include
the other front leg, then the back legs.  Other than that, she was fine,
with  no apparent anxiety or behavioral change.  This over- grooming of
her legs became established as a permanent habit, though.  A year later
she (being a long-haired cat) resembles a sheep.  I am not going to have
her put on Prozac to address the situation, as she is perfectly
"herself" and happy, it might not help, and I'm not about to expose her
to yet another possible iatrogenic affect of yet another treatment.  

All told, I am more leery of medical intervention than I was to start
with, and somewhat less likely to just go along with recommended
treatments unless one of my cats actually has symptoms.  

What is quite different in your case is that Deetoo apparently has
gingivitis.  Of course this must be dealt with.  At least you will have
two opinions after the specialist has seen Deetoo, although I'd be
suprised if a dental specialist didn't recommended whatever full
state-of-the-art dental procedure he/she has in his/her bag of tricks.  
I would just caution you to be conservative, and to consider Deetoo's
age and whether she has discomfort, in making your decisions.

Diana