Most are obvious why they haven't sold (steep slop, water/environmental issues, power lines) but occasionally I find one that would work with these new assumptions.

I think having a strong lease is one of the most important elements in all this. 

Greetings, I am a full time employed environmental consultant in NC.  

Knowing your market and your numbers are also key elements to your potential success.

Most liens are removed after a foreclosure property sale, but certain liens may remain.Here are some examples:Any lien recorded on title prior in time to the foreclosing mortgage.First Mortgage (if the foreclosing mortgage is a second or third mortgage)HOA or COA assessment liens (in certain states)Mechanic’s Liens (in some states)Government liens such as state and federal tax liens, city or county liens, US Government liens.IRS liens (IRS may buy the property within 120 days after sale at the price paid at foreclosure sale)Code Enforcement Liens, Environmental Liens, and Utility LiensChild Support Liens"Listing agent, seller's lawyer, and their title company have all told me it's clear, but I'm just doing my due diligence because this liens exceptions list is provided by auction.com.

Now, land contracts might not come into your business plan at all -- but if they did happen to be a big element of your plan then you would sure want to know about that before you went to the time and expense of getting a license. 

We also make it clear when we do so, that moving forward it will be tenant charge unless the plumber reports tree roots or something clearly beyond tenant control.4) Also during move-in inspection, particularly if the tenant is new to living on their own, I would review operation of certain basic elements to ensure they DO know how to use them.

Subdividing raw land is not for the inexperienced, you will need to know about subdivision laws, wells if applicable, perk tests if applicable, utility installation, zoning, deed restrictions, flood zones, phase 1/2 environmental tests, legal access, and I'm probably forgetting a couple. 

Knowledge - negotiating skills and being pro-active are the elements required to make deals profitable.

Show up on opening day to collect your deed.Oh right... first do a title search to make sure there isn't $500k owing and somehow find out if there's an environmental issue.