For the good of the game and as courtesy to the other players you really should fix your ball marks. It only takes a few seconds. I fix mine (if I hit the green that is), and usually 4-5 others on every green.
One problem with standard fork shaped ball mark tools is that they are used incorrectly. Most people stick the fork in and pull up the middle of the mark. All that does is tear the root structure, leaving a brown spot that can take weeks to heal.
The proper way to use the forked too is to pull the edges in from the sides. When done correctly the mark will not leave a brown spot and it will only take a day or two for the mark to heal.
Clearly the best golf tool out there for doing this process right and helping out the greens is the “Mark Mender” from www.markmender.com.
The Mark Mender is a spring loaded dual fork repair tool which fixes marks the right way, from the sides. The forks aren’t long enough to really damage the root structure, just long enough to pull the edges in. And since the action is from two sides, the repair is very even and uniform.
When not in use the mender closes tightly to fit comfortably in your pocket.
Included with your Mark Mender is also a magnetic ball marker. Mark Mender can even do custom print with your logo in the ball marker for you for promotional items or sales at the course.
You can buy a set of two Mark Menders for $19.99 at their web site. Not the cheapest repair tool around but it will be the only one you’ll need or want to use.