It's called: professionalism.If you like him and want him to want to work with you regularly, then strive to be the kind of customer that is a pleasure to work for i.e. pay him on time, don't micro-manage, be appreciative, etc.  

For sinks, and tubs, I would think twice if it is for a rental property - you cannot control the cleaning agents the tenants use.

Two out of three bathrooms need new tile, the main bathroom just needs a good cleaning, other than that the plumbing and fixtures are great in all bathrooms. 

Make a lower offer subject to a reserve public auction, offer the seller a 10% hybrid (10% of anything you get over what you offered), make full disclosures, get right of possession (so you can clean the house up and show it to prospective buyers), build in an extension in the event you need more time and use banking days for settlement.

Do I have to start applying to different brokers as we regularly do in Corporate world?

Can you see any sewer clean outs close to where the house was located?  

As far as I know, he's not sitting on a bunch of cash to fund rehab but title is clean and he could "owner finance" since he owns it outright. 

If you are worried about liability, get an umbrella insurance policy, plus regular insurance for the rental property.  

So we got a contractor to remove the boards, cleaned up the concrete, sealed it, and put in new concrete/epoxy floor.So what do you guys suggest for us to do to fix this problem?

I have contact info for team members here in KC that I use regularly.