Sexual assault could still be used if a whiff of impropriety should exist but evidence could also be manufactured. The process is about damaging optics and hoping that something sticks.
No human is perfect and dirt could be found. If not it could be manufactured..
Money irregularities.
Defending a nefarious criminal could be used to sully.
Family, employment, relationships, sexual promiscuity, scandal - anything can be used or manufactured to work against a nominee.