Maybe this isn't an issue for the large population of Stack Overflow users, but more so on the SF/SU sites (possibly related: How do we grow the Server Fault and Super User communities?).
I feel that format of the site, and the process of obtain answers or comments is not conducive for troubleshooting difficult problems. Troubleshooting is often a linear process where you ask a question, obtain suggestions (or answers), reply with new results, and eventually the back-and-forth comes to a conclusion or solution.
Most tech sites just operate forum-like software to handle this (or even news group style), which I feel personally works quite well. However, the SOFU/Yahoo style of here's-a-question; heres-an-answer seems "clunky" for problem troubleshooting.
On SOFU, the process usually goes like this:
OP: Asks a question, usually missing some details
Commentor: Asks for more details on the question
Answer: Gives a vague answer based on the question
OP: Edits the question with more details
Answer: Possible solution (gets upvoted)
OP: Comments on the answer that the solution didn't work, gives more results
Answer: (after reading the question, sorting though and reading the other answers and comments) posts a working solution
OP: (hopefully) accepts and comments on the answer
<10 days later>
Answer: (new user) Hey, I'm having a similar problem but the solution didn't work. Any more ideas?
The Mob: Down votes the user into oblivion...he never gets an answer and doesn't return.
After all of the up votes and down votes, the above turns into a jumbled mess on the site.
On a different site, I have an issue that I have been working on for 6 months. I occasionally add more information and people bump the thread up with their tests results too. We have eventually narrowed it down to a bug in the vendor's product which occurs in very specific configurations, and were able to come up with a work around once we determined that. Troubleshooting like that could never happen here due to the Q&A format.
So, uh, I guess my question is - how do we improve that?
For some examples, just search for "error" on Server Fault. You see a bunch of questions/answers that are hard to follow, don't come up with a solution or everyone just gives up. :(