How accurate do you think it is and how does it compare to actual MLS that realtors use?

., the court found that in determining unconscionability, the trial judge may consider: 1) the amount of the proposed rent increase; 2) the landlord’s expenses and profitability; 3) how the existing and proposed rent compare to rents charged at similar rental properties in the geographic area; 4) the relative bargaining position of the parties; and 5) based on the judge’s general knowledge, whether the rent increase would shock the conscience of a reasonable person.In my opinion if you're basing the increase on market conditions and not on trying to take advantage of anyone or increase the rent as a way to eliminate a tenant you'll probably be fine.

As for the dental, you can compare the market rate to other office in the area to access an economic value but having your own building and leasing it to your practice has other benefits ( taxes to name one).

When you have large cash flow (compared to your overall debt), rebuilding or fixing your credit becomes reasonably simple.

I would look at the dollar amount you'd be getting during this time and compare it with the work that you will need to do after they move-out.  

@Dean HulsingOnce you understand the environment in which the business operates (local tenant population, average rents, physical and economic vacancy rates, the growth / decline of the local economy, the risk of the local economy (i.e. does most of the tenant population work for a single (cyclical, declining, growing) employer)), then you can compare the business (property) to its peers and evaluate its shortcomings and potential.After the above, you should be able to put a value on the business and, if it looks to be a profitable, long term venture, issue a Letter of Intent (LOI) with your offer and deal framework,  If accepted, you then dig-in and conduct the formal diligence.

@Curt Davis Have to agree with @Ben Leybovich and @Steve Vaughan on comparing an investment to a car.  

Then, check them out for details that compare to yours, including age, condition and extra goodies, like shop buildings. 

Comparing apples to apples.

That way you search the area exactly and you can then figure out whether they are comparable by clicking on them individually.