I would buy some bleach, scrub until its gone, and let the buyer know it is gone. 

I use a Bissell Spot Bot to hands free deep stains in carpets while I'm scrubbing something the kitchen.

I believe I also detected at least a hint of actual smoker smell underneath.I'm so bummed out because everthing leading up to that day was going great, but as we were looking at the house, I couldn't think of anything else but the fact that the seller was a smoker.I'm now looking at options for smoker remediation, such as scrubbing the hard floors with vinegar, replacing carpet, painting all walls, cleaning or replacing AC duct work, ozone machine, etc.

We have purchased a list and are scrubbing and evaluating what we would offer on the homes to compare to what they are auctioned for.My question, any advice or things you would share with someone who is preparing to go to their first foreclosure auction? 

@Allen - along with your first 3 ideas, I also thought of a 4th - I could scrub the list according to my investor's criteria, get the thumbs up and act as their representative at the auction - like an "auction bird dog"...

Probably NEVER heard of Soft Scrub, and2.

You will need to scrub the toilet daily with bleach or ammonia in order to prevent "viruses".

there was cat pee and human odor throughout the house, the front door had been smashed in and it was without a security screen, the kitchen bench tiles were breaking off and the wood underneath was sinking in due to it constantly being wet and moulded out, the skirting boards were disgusting and the shower had so much soap scum that it took me 8 times with bleach and hard scrubbing to get it halfway decent followed by another 6 times to get it to where it was clean enough.

the first is oxygenated bleach...you can find it on the net and i use it all the time to clean my grout in the kitchen...you mix it and let it dwell for around 2-3 hours, scrubbing lightly as you apply it.

The whole house had to be scrubbed and then repainted and he still had stuff in the basement and the garage.