Instead of blaming the signal on a lousy ground, quickly connect that ground clip and test your assumption. Never accept something that looks awful. Convince yourself that either it's actually OK, or find the source of the problem. Walk through your lab. Unfortunately, too many of us seem to think the vertical gain knob is welded into position.
Every instrument is a lying beast, a source of both information and disinformation.
The scope is no exception. A 100 MHz scope will show even a perfect 50 MHz clock as a sine wave, not in it's true square form. You have to know your tools to use them effectively. We digital folks deal in ones and zeroes and tristates. Each condition means something.