Yes, I am a C coder. The variable names use awful Hungarian notation, but are often otherwise tersely named beyond that. It could use more whitespace to signify logical blocks instead of running all the logic in a function together. It's well commented except for the confusing parts, like the concurrency logic and the memory management, which seems rather backwards.
By contrast, both the Linux kernel and WebKit are far more beautiful codebases than SQLite, and also deal with far more complexity. If SQLite's the best you've seen, you haven't really seen much...
So, I have to admit that it's been a long time since I've read the code (version 2.x). I don't find Hungarian notation offensive, as long as naming conventions are consistently applied. If they aren't consistently applied in SQLite, then I guess that'd be a problem worth complaining about. I also don't find terseness and compact functions offensive. Whitespace is good, but not mandatory, as long as there is consistency...humans are adaptable, and once accustomed to a particular whitespace convention (whatever it is), it's usually fine. More lines fit on a page, anyway, and that has some value.
So, even if naming conventions are inconsistent and there's not enough whitespace, it is still a nice piece of code. The interfaces are very nice and clean (which does apply to internally used interfaces, as well, as I recall it), which is extremely important. It is also among the best tested pieces of C code in the world, with ridiculously high test coverage, which is good, too...it also means it is better documented than a lot of code, since the tests tend to provide a second tier of code documentation (you can see how the interface, both internal and world-facing, is used and what it's supposed to return).
I won't argue that Linux or WebKit aren't nicer. I've spent more time in the Linux kernel sources than any other major C project (except maybe Squid), and it is definitely a really great codebase. I don't know WebKit, at all, so won't comment. Linux has dramatically less test coverage than SQLite, and is also tersely commented and documented. I kinda suspect your opinion of the SQLite bits that are poorly commented comes from the contrast with the places where it is commented in vivid and verbose detail (I seem to recall there was/is some form of literate programming going on in SQLite, but maybe that was another project).
By contrast, both the Linux kernel and WebKit are far more beautiful codebases than SQLite, and also deal with far more complexity. If SQLite's the best you've seen, you haven't really seen much...