Of course, you'll have to clean and restock supplies, linens, etc between rentals and figure out how to find short term winter tenants.  

I'm considering starting an apt. prep business (cleaning, painting, minor repairs) and would like to get your first impression as a property owner and/or manager.

Renovate the exterior so that it is clean in appearance and can easily accept the tenants awnings and signage.

I did a four year apprenticeship of cleaning oil boilers and crawling into attics, I think I can handle a potential buyer/seller lead saying no to me being their agent.

Zillow, trulia, and facebook seem to be great resources that they're not using, so I can add those as well. it also seems that it takes a month for them to clean, then they advertise the next month, for a longer turnaround time. 

It is a large 2 story older home and needs about 2500 dollars in roof repairs, due to gutters not being cleaned out and Facer boards rotting away.  

The only real risk to you is the fact that the property will now have to appraise for $61,000 in order to get this deal done, rather than $58,500 if the offer were "clean".As a contingency, you should discuss with your agent what your plan will be if the appraisal comes back short. 

Put all of the information on a nice clean spreadsheet then shop the deal.  

Unless tenants have nice stuff and keep the place clean it's hard to get top dollar for occupied units.

If the place is not cleaned or rent is not paid, they are both liable.