I think this is by definition unfortunately. They wouldn't have made the selection otherwise.
Their party leader is objectively an unscrupulous peddler of untruths and fictions, past, present and future. They must all know this, just as I am sure he knows himself that what he's saying isn't true, but it is in their assessment their best route to power - the only real goal of Boris Johnson.
I'm afraid I agree. The Conservatives used to be a party that I disagreed with, but which had some principles. Now they seem to rapidly gone the same path as the US Republicans.... Willing to do anything, no matter how unethical, including freely lying, in order to keep their Great Leader in power. Those senior figures who want to stay honest or true to their principles appear to have, on the whole, either been kicked out or quietly left.
Labour by contrast has moved in a direction that I do not particularly agree with, but people in the Labour Party are still, on the whole, motivated by moral principles (albeit in some cases, IMO unrealistic ones), and seems to be conducting a campaign that is relatively honest (insofar as political campaiging usually goes). I have many doubts about Corbyn, but I'll choose him any day over just about anyone who is still in the Conservative Party. And, to Labour's credit, they are standing a fair few candidates who are not really Corbyn supporters.