Currently, the WikiAnswers system of trust points hasn't changed - you can only add trust points, and you can only recommend from a question the user has answered by going to the contributors tab and clicking "recommend".
There was a correction to a glitch which had awarded excess Trust Points in December 2009 and the excess points were removed.
No, there is currently no system for subtracting Trust Points. It's a purely positive, incremental system. This may be something we will introduce later.
Trust points do not entirely help you get hired to work for WikiAnswers, since actually getting paid to work for WikiAnswers is different from the amount of trust points you received online.
Your total WikiAnswers contribution points are calculated as the sum of all of the contribution points you have earned. These include first answers, edits, organizational actions, questions asked, and community contributions. All of these points come under the heading of "Contributions" in your WikiAnswers profile. Trust points are slightly different. Contributors do not directly earn these points through their contributions; they are awarded trust points by other WikiAnswers users. Therefore, trust points are not counted as contributions, and do not add to the contribution points total in a WikiAnswers profile.
There is no limit as to how many trust points a person can earn on WikiAnswers. Currently, the highest number of trust points held by a person on this site is well over 8,000.
The Trust Point system allows contributors to vote for a WikiAnswers member whose contributions you think are worthwhile and legitimate, and clean. Please see the related links for more information on trust points.
Many have.
No, you are not able to hide your trust points from other users.
No, neither giving nor receiving trust points count as contributions.
There is no maximum amount of trust points one can have on WikiAnswers. At present, the highest amount so far is well over 8,000.(For a list of users with the most trust points, see the Related question)
Currently, there is no badge for accumulating 50 trust points on WikiAnswers. The badges are awarded for the following: 500, 1,000, 2000, and 3000 trust points.
WikiAnswers uses trust points to distinguish trustworthy, good contributors from others. Answers from contributors with lots of trust points are often well-written and helpful.