From my own personal experience (evidently the police do not appreciate someone trying to get somewhere as fast as possible) and as an attorney representing traffic clients, I think it is safe to say that in practically every instance it is a good idea to contest a traffic ticket.
The first thing to note is that there is no harm at all to do so; the worst thing that could be visited upon someone who contests a traffic ticket is wasting some time down at traffic court and losing in court. Pleading guilty is, obviously, an automatic loss so blowing a couple of hours to possibly win or plead the charges down does not seem like a huge risk to me.
The benefit to contesting tickets is obvious. First, it delays the time in which you need to pay the fine if money is tight. Second, there is a good possibility that the municipality will negotiate with you to plead down the ticket to some lesser charge which generally results in a lower fine and fewer (if any) points on your record. Third, if you have a good defense and want to risk going to trial instead of plea bargaining, you could win and have the ticket dismissed altogether.
The benefit of winning in court is pretty clear as the ticket is dismissed and therefore no fine and/or penalty is assessed on your driving record accordingly.
The benefit of plea bargaining could have significant implications. Keeping plea bargaining in mind is important because, if we are honest with ourselves, when the police pull us over it is generally because we were actually speeding or breaking some other traffic law, so winning at trial is unlikely. So, plea bargaining gives you another way to try and lessen the impact of a traffic violation. Obviously it is always good to have a less severe penalty and lower fine assessed, but the implications go further than that. Plea bargaining which results in no or fewer points on your record could mean the difference between insurance rates increasing or staying the same, being on the brink of suspension or still having a buffer, or getting your license suspended or not. So, needless to say, it is advisable to explore all of your options in court when you get a ticket as it may be the difference between driving and not driving.
Though not directly related with contesting tickets, whatever you do you must pay any fees and penalties assessed. I can’t tell you how many people call me who discover, perhaps years later, that they are driving on a suspended license due to unpaid fines from years before. The suspension term, once it catches up with you, would begin now and will cause you much heartache for something you could have easily dealt with before.
Finally, it is important to remember that with each year of clean driving your driving record will be reduced by three (3) points and if you can keep your record at zero points for a year the Commonwealth will reward you by treating you as if you had never previously received a ticket. Therefore, contesting a ticket can play a significant role in maintaining a decent driving record.