All us WEIRD (western educated industrialized rich democratic) countries seem to spend a really embarrassing amount of time talking about the pointless minutiae surrounding our candidates for office and their personal lives.
We are also prone to backing very crap candidates based on personality, rhetoric, appearance ie: things that have nothing to do with being a good executive or legislator.
I think we should ban names from the election process and just have each party submit their ideas in writing and let people vote based on those submissions.
Who determines the percentage?
People have access to the information now to know who the liars are, but they choose to ignore it.
I think it could be as simple as party x claims they will do thing a, b, c and then after their term in power you assess if they achieved those things. The parties who make the claims will need to back up those claims with real milestones that would become performance indicators of partial or full success. The milestones must be easy to assess and leave no room for interpretation. Just like in a legal contract, if you make the wording too vague and hard to interpret, then your contract won’t be enforceable in court.