There have been two major impacts of Watergate on the nation's political processes.
First, members of the media have become obsessed with scandal. They are constantly trying to catch politicians doing wrong because they feel that this is what the media needs to do in a democratic system. Some scholars feel that this distracts the media from trying to report on more serious matters (the Anthony Weiner scandal is an example of this).
Second, Watergate has made it so that the parties use scandals and hearings to try to attack one another. This is especially true if the president is not of the party that controls Congress. In such cases, Congress will try to find any sort of hint of scandal they can so they can hold hearings and make the president look bad. This has seriously corroded the way that our political system works because the system of Congressional hearings is being used more to attack the other party than to actually get information.