drug use will definitely be a problem, esp. if it was within the last couple of years.

you're ~35 and admit to smoking a buncha weed and maybe some other stuff in your college frat 10+ years ago? not much of a discussion topic, esp. if you've had a steady job, house, family, etc. since then. doesn't have to be short, you could have been called Mikey Pipes for all 4 years of school... just that it was a phase, and it's been long gone.

smoke weed and pop some lsd 1.5 year ago? that could be a problem, esp. if you're still living the same life essentially as then.