Clean install

Having an issue with screen flicker in certain sections of iTunes and other related problems with it, I visited the local Apple store on two consecutive days. Most annoyingly and perversely, this problem which worked like clockwork at home never appeared there. The first time, they re-installed iTunes. The next day the fellow had me endlessly repairing permissions, about 7 times before I gave it up, via Disk Utility, and there was a very long list of them. He finally departed on personal business and eventually I mentioned to the fellow taking over for him that the permission repair seemed to be repeating itself, exact same files listed, and in effect doing nothing. He noted this and said repairing permissions was often a waste of time anyway, accomplishing nothing. Maybe he should have told the other 'Genius' as much.
Anyway, they both knew I had reverted to 10.5 from Snow Leopard in frustration. He suggested I do clean install of Snow Leopard and see if that fixed the problem. Since I asked him how, he told me specifically how to go about it, with one aspect of the procedure something I never would have known otherwise.
When doing a clean install of 10.5, I did that from the option of the Apple system disks. But this was different. I started from the Snow Leopard system disk, holding down the 'C' key, but after the dialogue box asking language preference then opened Disk Utility and partitioned the disk, choosing 1 (one) partition. I had never done this before, or would have known to do it or how. It took but a few seconds and apparently in that time entirely erased the disk. I then continued in installing Snow Leopard, which took about 30 minutes to complete.
My feeling is this OS still isn't as stable as it should be, but issues with iTunes I had were resolved. Moreover the lack of a screen saver, and sleep issues I had when upgrading to Snow Leopard now resolved in doing a clean install of it. One anomaly just prior to all this was a purchased movie from iTunes never downloading, but that may or not be related. One issued not resolved was the Opera browser working very slowly after Snow Leopard; this only resolved in changing from the latest version of Opera to their beta version, 10.10, which inexplicably now works as it should.
One thing they told me at the Apple store is that it is problematic reverting to a former OS; that may be one reason so many permissions were out of whack. Since my files had been backed up to Time Capsule during the use of Snow Leopard, apparently infused with that OS, problematic to anything prior. I can vouch for reverting to 10.5 being one big pain, and quite possibly always an imperfect solution. If having upgraded to Snow Leopard, your best bet my lie in learning how best to live with it. That might include a clean install of it.