Lots of great connections all over but we also have a very strong and active contingent here in MA on here so make sure to find them (Set up some keyword alerts to find out about local topics) and get connected.Besides doing that on here make sure to get out to some of the many local investor events we have.  

Anytime I have purchased sub2 I run through all of their options, I believe I saw a handwritten chart that @Brian Gibbons goes through with a seller on a thread that is similar, sell retail(MLS/RE Agent/showings/offers/contingencies...etc), rental (become landlords/hire PM/still have expense of prop/may be positive investment for them), sell to me either at a significant discount (wholesale price) or I can put some money in your pocket, take over payments and they have their hands clean of the property.  

I know on financed properties you refer to all cash offer to indicate that the buyer will receive all cash at closing and a financing contingency usually indicates financing but not sure on the legal wording.

Here is an example of a 12 unit I looked at in Chicago electrical $2,400.00 water $1,500.00 gas $8,000.00 insurance $3,600.00 property taxes $6,200.00 maintenance $2,000.00 garbage removal $1,200.00 contingency $4,400.00 total expences $29,300.00

I do not have the property under contract yet, as this whole deal is contingent upon my negotiating skills with the bank, if that's even possible.

As far as current tenants, I'd want  to make my offer contingent on a full review of all their paperwork -- application, background check info, full lease, list of move-in discrepancies if they turned one in, record of any late payments or lease violations, and the ability to screen them if any info is missing.  

I would still want to do it contingent on a home inspection as I am not experienced enough to wave that part of the offer.  

Then make an offer with a contingency like getting financing. 

INSPECTIONS: This contract is contingent upon the Buyer’s and Buyers’ Partner inspection and approval of the property prior to transfer of title.

You can request to see bank statements to look for direct deposited rent; whether they show you those or not is another matter- so you might want to make that a contingency in the purchase agreement.