I agree with you - a jerk or lazy person will be a jerk or lazy person regardless of being a CNA too.
My mentor told me NOT to take the CNA class and enjoy my summer off with my kids and dh prior to starting nursing school because school would be all encompassing. Plus, I would learn all the CNA stuff at the beginning of nursing school.
I've personally known nurses who were CNA's and LVN's and some won't answer a call bell, won't help someone onto a bedpan, won't help someone up off the bedside commode, refuse to make a bed, etc. Others who have been CNA's are great team members.
My philosophy is to be a hardworking member of a team and I appreciate all the hard work the CNA's do and I help out. While they are showering the patients, I make the bed. If they are busy with another patient and I have a patient waiting to be discharged, I take the patient out in a wheelchair.
The only thing that matters in this situation is what kind of person you are. Will you be appreciative of your team members and help out if you can? Then don't worry about the CNA class. Concentrate on your full plate - don't add stuff that isn't necessary.
Having said that - if you really want to be a CNA and are already a wonderful person, go for it.