Solved! Go to Solution.
If you have a lot of existing scoring programs and don't want to go back and modify them, another approach would be to set up a trigger campaign to reset the lead score to 1 if any scoring activity happens to result in a negative score.
Smart List
Trigger SCORE IS CHANGED
Score Name LEAD SCORE
Constraint NEW SCORE LESS THAN 1
Flow:
Change score
Score Name LEAD SCORE
Change =1
Schedule
ACTIVIATE
You're technically not preventing a negative score, but if you do go below that threshold, the score gets reset to your minimum.