I'm looking at your icon in question "photoshop cs" and I am unimpressed. I rated it a 6, and as my general ratings go I look at things like this.
1. Did the person make it? If so I will almost always give it at least a 6 just out of the reason that it is original work. If the person did not make it and it is ripped work/copy pasted, I start at a 1. After I have the 1 in my mindset I look at details, did the person at least do a good job copy and pasting the thing? Are there jagged lines? Problems with anti aliasing? Though my initial thought is at a 1, the more work put into manipulating an image, the higher I will take it, I've actually given completely ripped work 6's before just because they did it so well.
2. Does the icon work well, (if for dock, or whatever the work is intended for). Icons specifically have many necessities to work. Icons must be easy to identify the size of a dime, or cd. Which means simplicity is often a must. They need to be pleasant on the eyes. And most of all they need to clearly identify what they are for. Which is why just copy pasting stuff like a mobile phone doesn't do diddly. No one knows what kind of phone it is when it's the size of a stamp, nor do most of them care, they want to know it is a phone, not that its a "220zx 640 special edition gaming capable wireless es2000 picture phone" from verizon. Thinking in a way that pictographs work is your best bet to understand that.
3. The final thing I look at is, is the icon of any use? Photoshop icon, hell yeah. The flag of germany...probably not. Most anything can be used, and often people have excuses for it, i.e. a picture of a shoe to launch "run". but just a picture of a shoe doesn't signify run.
The first 2 are very important, the 3rd is more open to interpretive opinions, which is why I never completely base a rate on it.
Though I'm sure you probably care less about all that, you're still worried about photoshop. My biggest influence on the rating of your photoshop is that doesn't have the polished beauty that your kazaa and quicktime icons do. (and i'm not talking "aqua effect")
Other than that, I still believe people should be able to honestly rate however they find necessary, in the land where middle is a starting point, a 2 is no more out of question than an 8. People only bicker about low ratings though, instead of thinking, "oh well maybe there is a reason for it". people always assume they are being screwed over and that their work is perfect with no flaws or room for improvement.
Keep in mind, everything starts out as a 1, and many deserve it in the end. It's not easy to get a good rating, but those that deserve it always seem to. On a side note I've given out plenty of ones and 2's and so forth, I've only given out two "10's" ever. 1 signifies total crap, which I've seen and feel justified giving when I do. 10's declare perfection, and even though I've given 2 10's, I still don't feel they were perfect. If people really consider that a 10 means perfect in every way shape and form, less people would be thinking things deserved them.