You are probably going to go broke at 6-Max on that second hand reguardless, unless somehow u can put him on a broadway straight.
About slowplaying, I find that all really terrible players overuse the slowplay because they are afraid if they show any agression it will give their hand away.
Look for a delayed pause then a call, from my experience this means a trap and usually sets off warning in my head. A quick call for the most part is a genuine chaser and I usually treat him as such..