I followed a link to a Something Positive strip, and suddenly flashed on why I’ve never been able to follow this webcomic. It’s because I can’t read the thing. Literally.
Maybe this is just me. Something Positive has a large and devoted following, so obviously many people must be able to see words in those cramped, blurry masses of text. I can even do it, if I work at it. But it’s enough work to cancel out any enjoyment I might have gotten out of the strip.
For comparison, here are some word balloons from some webcomics I do follow. In each case, I grabbed the largest word balloon I could find from a recent strip.
Sordid City Blues by Charles Schneeflock Snow
Notice how readable this is, despite the small type size. That’s because Snow uses generous linespacing and a good font, and breaks his dialog up into small pieces. This was the biggest single word balloon I could find in a recent strip, and it’s only got 13 words. Snow makes his living as a graphic designer, so he knows how this stuff works.
Scary-Go-Round by John Allison
Large, clear type. Dialog broken up into small pieces. Again, 13 words.
Questionable Content by J Jacques
At 36 words, this clocks in as the largest balloon so far, and the type is pretty small, but mixed case makes it readable, as well as allowing Jacques to use all-caps for emphasis. The whitespace above lower-case letters means you can get away with less linespacing. It would be even better if he used a taller, narrower word balloon. And it suffers a bit for being placed against an open white background; I probably should have included the balloon borders in these images.
Templar, Arizona by Spike

I’m not actually sure that Spike uses computer lettering. Possibly she uses a font based on her handwriting for most of the dialog, and then hand-letters special stuff, like the “God” in this balloon. In any case, the large lettering, extensive use of italics and boldface and underlining and occasional other effects, and the breaking up of long speeches into smaller balloons (this one is 20 words, but it’s one of five balloons in that one panel, in which only that character is speaking), not only makes the text very readable, it conveys the rhythm of actual speech. (Update: Spike commented below; all the text’s hand-lettered.)
Now, here’s Something Positive by RK Milholland

That’s 60 damn words crammed into one big balloon, all caps, with practically no space between the lines, and a font that has almost no space between the letter I and adjacent letters. (Look how the I almost blurs into the N in “insane” and “screamin’”.) This is a strip where much of the humor is conveyed through dialog, but the dialog is presented with almost no care. Look over that word balloon again, then look at the middle panel in that Templar, Arizona strip, and imagine how Spike would have presented it.
It may not be fair to compare these strips, since all of the first four are larger than Something Positive. Sordid City Blues is 900 pixels wide, and Questionable Content is a massive 1418 pixels tall! But Milholland is the one who chooses how to lay out his strip, and how much dialog to put in it. He can make it bigger, or write less, if he wants to. An advantage of webcomics as a medium is that they come with very few artistic constraints.