If the question is worded correctly a url isn't needed. Instead of pointing at a specific page and saying 'why does this do well' the question could be more general. Describe the page and what is on it (in seo terms, ie title, keywords etc rather than exactly ie blue heading). Give the reasons why it shouldn't be at the top. Mention factors which may increase it's ranking. Spell things out instead of just pointing to a page and expecting everyone to see.
Then the discussion becomes about what really is and isn't a good page and gives the oppertunity to learn about and discuss the situation of an apparently bad page doing well. The answersd can be applied to many things rather than just teh page in question. It takes a small amount of extra thought at the start but I've seen it done here many times. There are times when a specific example makes things easier, generally when discussing a visual aspect of a page, but it's not always necessary.
I don't think that the mods here are really more likley to remove a url just because the person dropping it is new or less well known. I think what actually happens is that the people who have been here longer have a better feel for what is acceptable and are therefore less likely to post something that needs removal. Experience makes a difference.
One thing I find very refreshing about this forum is the lack of signatures. I hate them. They are (often) slow loading, (always) distracting and don't add anything to the matter under discussion. If I'm interested in another member I can look at their profile but I don't need that information as I read the posts. I have stopped reading a couple of other forums purly because I had trouble picking out the posting from the stuff under each post.
I hadn't even dreamed of many of the spam techniques mentioned in this thread but now I'm aware of them, I see them around the place. When I see one here I get a big smile and sit back for a minute waiting for the Mods to move in. I've never been disappointed :) I think one of the best ways of keeping this kind of spam as low as possible is to make it known that it's not tolerated, and quickly removing anything suspect is the best way to do this. While there is a somewhat hardline attitude here to url drops and site promotion, I think it works and is worthwhile.