Sure, there are many non groomers in the world that do a very nice job grooming their pets. But more often than not, we see pets coming in that looked like they had a run in with a weed whacker.
'my owners bought a pair of clippers...'
'they thought it would be easy.
When grooming cats it's really important to remember two things. One, THEY ARE NOT DOGS. Two, THEY DO NOT CARE. Generally speaking, your cat wants to do whatever it is he wants to do, and that usually isn't sitting quietly while he's brushed or clipped. Especially if you're not familiar with how to do it. Cats move quickly and unpredictably and without warning. That means scissors should never be used on them. I've groomed many cats with owner attempted haircuts that ended with a trip to the vet for stitches.
'leave this to the professionals'
This cats' owners tried to clip him at home. They found out pretty quick that getting an even clip on a cat is pretty hard! Luckily, neither party was injured during the attempt. Clippers are far safer than scissors, but it's still possible to cut a cat by using the wrong blades, wrong technique or just bad luck. Even the pros (like me!) have had a cat move just the wrong way, at just the wrong time and get a nick. With training, the right tools and experience, we keep this type of accident to the minimum.