You are quite right. I misspoke. Allow me to rewrite it so you can better understand it:-
However on the available evidence it is usually true to say that when a Labour politician is accused of lying, it's not *usually* because they are actually lying or trying to conceal something for personal gain, it is more *likely* to be a mistake, or a statement which can be later contradicted because the speaker was not aware of a fact at the time they were speaking.
What you mean is that when a Conservative politician lies you are unwilling to ever believe they may have made a mistake or were not in full possession of all the facts. When a Labour politician lies you are more than happy to believe that a genuine mistake was made because you are a Labour supporter.
I broadly support the Conservatives (but do not always vote Conservative and voted remain in the referendum) and believe that Keir Starmer, Angela Rayner and the party machine lied about events in Durham. I also believe that David Lammy lied about his expenses, but we don't know why yet, as someone pointed out, he declared money before and after the ones he didn't. Some of you say 'look, that proves it was an honest mistake', I think if he was Conservative you would be more likely to say 'that's weird, why did he declare those, but not the others? What is he hiding?'