IME, an account reporting as "Unknown" vs. "Paid" causes a slight decrease in score (~5 points).
I disputed a charge on an account that I normally pay in full each month. The credit limit is approximately $15K, and the account has been open for nine years. The account normally reports as "Paid", but as of last month, it's reporting "Unknown" due to the dispute. I saw an immediate score drop (there were no changes to my report other than the account with the disputed charge). The charge is now out of dispute, and my statement will close this weekend. Once the bureau updates, I'll see if the account is reporting as "Paid", and how my score is affected. I'll update this thread with the results next week.