“Trust but verify.”
Quite right, but how to verify under these circumstances?
We don’t have any complete unknowns, as the example described. We can easily look at every candidate’s history and determine whether we believe they’re conservative or not. Verification is simple in most cases - how did they vote / endorse policies / author laws in relation to their claim to be conservative?
Some will be more conservative than others (obviously) and
There will never be a candidate with whom you (or me, or anyone else) will agree 100%. Once we know their stances, the goal should be to determine whether the spots where they’re not conservative are acceptable or not. I find it helpful to prioritize my issues by “this is more important to me than that”. For me, the economy, immigration and foreign policy (specifically, how they will combat islamic terrorism) are #1, #2 and #3. For others, Abortion is the top thing. Or Obamacare. Or gun control.
I’m sure others have their own processes - not saying mine is perfect but then, the candidates are not perfect either. They’re just people. They’re not God. Expecting “perfection and 100% lockstep in belief or I’m not voting for you” is a mistake.