Fill in the foundation below.Check out the Start Here page http://www.biggerpockets.com/starthere Check out BiggerPockets Ultimate Beginner's Guide - A fantastic free book that walks through many of the key topics of real estate investing.Check out the free BiggerPockets Podcast - A weekly podcast with interviews and a ton of great advice.

Even behind the vynil siding could still smell like smoke when you walk up to house in the future. 

If you walk around those places around 6PM, you'll see most people with some kind of tech swag.

That said, don't walk into any situation blind; make sure you utilize all the tools available on BP and always ask questions in the forums when you are unsure of something.

If you do not feel good just walk away and go on to the next one.  

Its better to walk away from a deal than to take any deal which could turn bad.I usually track how many deals I'm making and how many I win.

Did the current tenants not do a walk-through?  

In such a situation I'd be looking first at selling the place immediately to walk with the profit, but that wasn't the OP's implied question.

Get the seller to agree to a deduct to cover it at closing, accept it, or walk.  

It'll open your eyes when you walk into a house as to what needs to be updated or repaired.