All politicians lies, regardless of gender, age, race, nationality, etc. the thing that a politician should worry the most is that when they are lying, they need to phrase it in a way people won't discover they are really lying, specially if you're a candidate to be a president, once you're one (a president, assuming you win) you can lie and say bullshit without fear however you want because you're now a president, but when you're just in the campaign process, you need to watch out for rumors, gossip, talk of mouth, etc. that anyone will do against you.
These two are very laid back in those aspects tho, they just spout whatever they want and they win loyal followers regardless, but when you take into account this:
https://en.wikipedia.org/wiki/Category:Hillary_Clinton_controversies
You're now not in the position to cause more controversy, that would damage your image and reputation, again, not that those two have a very good reputation anyway, but you just can't fuck up anymore specially during such heated moments, so when you're incapable of hiding lies or secrets, you cause controversy, said controversy can deal damage to your image, your image is what she relies to win or not the campaign, and also followers or people who don't want Trump.