TQ scores are calculated completely on conversions to the advertiser. So if you have domains that get 0 clicks, then they are not counted in your TQ score. The TQ score is updated every 7 days, technically on Thursday, but is based off of a 4 week weighted averaged with a larger portion being based on last week as opposed to the previous week.
Accounts are terminated for long term low scores. If I look at somebody who has a 1, I can usually tell why they have a low score. I personally would rather not terminate an account if I don't have to, so in many cases if somebody has a low score they will get an email from me or their account manager telling them to fix the problem asap. Sometimes Yahoo comes in and tells us to terminate a large number of the low accounts.
If you were a 10 in the first or second week in January and then you dropped this is because of the TQ scores being reset, so you can't really count on that TQ score of a 10.
trader - if you want me to look at your TQ score, send me a PM with your username as I don't know what it is.
Donny