Calling on someone for smoking weed in their own spot can lead to your own dangerous demise in some places.

If it's a dangerous situation that's totally different and cops need to be called.

This is especially dangerous if the lien holder has made any improvements to the property.

Where as long as they purchase as contractually agreed once the offer has been accepted then I'm in no danger is losing my funds, my 3,000 fee is only refundable should the seller change their mind on selling us the property. 

You can require the pet to be under the direct control of the owner at all times, droppings to be picked up immediately, and not cause a nuisance or danger to other residents.

If you are not %100 sure of what you are bidding on it could be very dangerous. 

What are the potential dangers to this strategy?

I hate to be the bearer of bad news, but you are treading in very dangerous waters. 

And that regret is dangerous because it induces sunk cost bias. 

For instance, I've seen many older homes that have beautifully newly-finished basements...but, get behind that new drywall, and there's old galvanized steel plumbing with maybe 3 years of service life left, outdated and dangerous knob & tube electrical, asbestos, structural integrity problems, or any number of other issues...the end result?