We usually only do preliminary research prior to viewing the property.

I'd wager any "good deal" you actually might of had you didn't recognize as the market seems to be doing really well there.Maybe get your real estate license and all those leads you can't convert as a wholesaler you might be able to pull 3% from?

Get a title company to do a summery preliminary report just to make sure there are no unknown liens, lis pendens, HOA etc.

Not a story, but I have found it helpful to put a list of preliminary questions at the bottom of my ads that they must answer to get more info/schedule a viewing.If they don't answer the questions, I simply don't reply to the email.

Well, those properties with rents that are less than 1% of acquisition cost are not going to be as wonderful for cash flow as your preliminary numbers seem to show.

:-P Lol jk, I use Redfin as a preliminary, then I have a realtor who actually knows what he's doing check me.

Too many people spend too much time worrying about all the preliminary things and in the end never get the deals closed. 

She has no case.She illegally subleted your property to an unauthorized tenet and profited from that action.She will lose immediately either in small claims court or a preliminary hearing.Don't lose any sleep over her crap and refer any additional communications from her to your attorney.In the meanwhile,I would start to eviction process with the current occupier of the property.

Unless he specializes in landlord/tenant law, I'd wager that most knowledgeable landlords have a better immediate grasp of those areas of the law than he does.

Look at this situation like a poker wager.