Why don't the Democrats use personal attack ads against Trump?

I don’t ordinarily care for such ads, but there is so much material. It is not advisable to mention his impeachments or crimes he has not yet been convicted of. What they can mention is his numerous business failures, refusal to pay contrators, loan defaults and the Stormy Daniels mess.

I remember when Nixon ran for president there was a line that asked if you would buy a used car from this man. Maybe for Trump it could be, would you lend money to this guy?