i think you have a great idea, but i would not limit it to the chain stores. If you want to start this type of website, i would recommend directing it at helping dog owners choose a groomer in general, not just focus on big box stores.
I worked for petco, and have known many petsmart groomers. Training is pretty much the same at both: if you have experiance in grooming, you can take a technical and start as a groomer if you pass it. If you have no experiance, you start as a bather/brusher and are then taken to academy after 30 days. acadamy last about a month (40 hours a week), then you return to your store, groom 100 dogs well, then are passed through the school.
now that you knw what is suppossed to happen, ill tell you what really happened. I was hired at petco, and had no experiance besides owning my own dogs (i had been riding horses my whole life, which was the main reason i was hired). I did not start as a BB, they started me right in the school (which goes against their own guidelines). I was told this was b/c they really needed groomers at the store i was to be working at. The instructor was AWFUL. she was very very old (had nothing to do with it, except slowness and hard of hearing), and was not a very good groomer. 75% of my "training" was watching dog shows and talking about the different breeds and cuts. the other 25% were bathing dogs, and reading from a textbook. All in all, i received no training to make me feel competent as a groomer. before i had to sign a contract stating i wouldnt quit or be fired for 2 years without oweing the company 2500 bucks for the school, i told them i was not going to be a groomer and would rather be a bather/brusher for awhile (ironically, what the company should have had me do in the first place). there were 3 others in my school at the time, one became my grooming manager, and while a great person and good with the dogs, she was very slow (could barely get 3 dogs done in 8 hours which is slow even for a newbie) and did not feel confident with the training either. the other 2 thought the training was great, but also gave horrible haircuts before being fired for too many complaints against them.
the training is only as good as the trainer. 4 weeks is not enough to learn grooming, but it is a good head start if the instructer is good. anyone who starts in grooming should know it is a lifelong learning experiance anyway, no matter where you recieve your training, you will have to keep up the educating long after you are in school/training. as i said, my trainer was awful, and it showed when you watched her students try and groom (including me). but the next zone from me had a trainer who was the us groom team, and was an amazing groomer. if i had stayed with petco, i would have gone back to the school and been taught by her. she was proof that amazinggromers do work for these places. I know many great groomers finally caved and started at petco/smart, and were very happy. they had control over the dogs they groomed, choose there own hours, and got benefits. for a groomer, who maybe has a family, working for a big box chain is a fabulous idea. and when a big box chain has a good groomer, that groomer makes bank.
training aside, the salon i worked for was great. the other groomer, besides the manager, was a good groomer and had a lot of repeat customers. the main thing ihated about working at petco was the store itself. They wanted the salon run like the store, which wasnt always possible. they wanted us to adhere to very rigid rules regarding opening/closing the shop, and would not budge when it came to our lunches. we had a very hard time with the store manager, who knew nothing about grooming. he would give customers refunds without talking to the groomer who did the job, making us sometimes wrongly lose out on commission, and would never order materials we needed for the salon.
i have also worked for a few private salons, and will say the belief that your dog is safer at these places is just untrue. i worked for a place that had heated cage dryers on dogs in a room that was 80 degrees with nothing more than a lttle fan (and ths was only in april in southern calfornia, i would hate to be there in the summer). this place also never cleaned between dogs (pens, tables, tubs, etc), had mold growing on all the walls, and was just a disgusting place to be in general. yet, she did more than 20 dogs a day (charged over 50 bucks for all the dogs), and is stll in business after 15 years. why someone wuld walk in there and leave ther dog is beyond me, but i guess people really do trust you if you just own you own shop. say what you want about petco, but when i worked there, we cleaned the whole salon top to bottom every single day, shut down if the salon was 80 degrees, and only used non heating dryers on the cages (and all dogs were hv-dried first).
i think people need to be wary of all professionals in the dog world. unfortunatly, there is no real was to judge how "professional" someone really is, except by the work they do. I always tell people to ask others for referrals when it comes to dogs. and to not ask just anybody. When you see a dog that is obviously well taken care of, you should not hesitate to ask that person what services they use, whether it be for grooming, boarding, vet care, whatever. you can go in and question a groomer all day long, but they are not going to be honest about the accidents they have had, or how they treat the dogs (if it is indeed bad). they all say they are great and wonderful, and the only way to know how it really is to ask people who use that person.