Just catching-up on podcasts and was listening to the Noah Lyles/Lance Brauman interview. I didn’t know who Noah’s coach was. The podcast intro said he coached both Tyson Gay and Veronica Campbell-Brown. Both have tested positive. So, why should I believe Noah is clean, too?
Firstly, think what you want—why should anyone care? They don’t know you.
Anyways, to give a good faith response, Tyson’s positive was demonstratively linked to Jon Drummond as the party responsible, hence why Tyson received a reduced ban for cooperation and Drummond received an 8 year coaching ban. Secondly, VCB split with Brauman in 2009 and tested positive 4 years after in 2013, and it was at a meet in Jamaica. So the connections made in your post are tenuous at best.
The truth is, with such wishy washy logic you can say “why should I believe they are clean” to most extraordinary athletes. You don’t have to believe they are but let’s not pretend you actually have any circumstantial evidence or reasoning to think so besides their performance level being high.
I'd say if it makes you feel better, you might as well believe it. Or just don't bother trying to speculate. History would say you are right to wonder, though.