Relying too much on PT reads?

I know preflop questions are a thing of the past now ... but I was wondering, as a rule of thumb, how much does relying on PT reads affect your play preflop?

This post might be results-driven since I get moderatly creamed 2nite, but here is an example:

A 40/20/1 vpiper raises from late EP raises ... folded to me in CO with KJo. Normally, against your average tag I would muck. Recently i've been saying "hm, he raises with the same hands I call with ... statistically my KJ can't be far behind if they are behind at all".

The flop comes K high or J high ... when it's all said and done im showing down top pair to a dominated hand like, QQ (with a jack out), QJ, AK etc. Are these just isolated incidents or should I continue to trust my PT reads?

Another example - 2 50+ players limp from MP ... I am CO with a marginal hand like, KJ or KJs. If the blinds & button are reasonably tight, should I raise & try to play KJ 3-way against 2 players who probably limped with garbage? Is it still correct to do so with KJs even though KJs plays well multiway (and risk blinds drawing me with trash)? I think I might be taking this "isolate bad player(s)" thing too far to the point where it's leaking my game, but I haven't played enough hands to be sure.