They can come from many areas -  some are or have been successful at flipping property and now have excess cash while others come across excess cash from other areas and know the security of real estate versus other vehicles.

Moisture meter only showed right in that immediate area.

I have a single unit with similar problems and it has problems with the floors being very cold, moisture build up, and of course mold. 

Any advice is greatly appreciated.8bd/4bth legal 3 unit Unit 1:2/1 TNT pays all, rent 550Unit2:2/1 TNT pays all rent 475Unit 3:2/1 rent 450Asking price 100kARV 140kDp 5% at 5k loan AMT 95kLoan interest at 4%Expenses:P&I: 453Insurance: 100 Water sewer: 100Prop tax:300Repairs: 147.50 at 10%Capex:147.50 at 10%Vacancy:118.00 at 8%Cashflow: 158.46Cap rate:5.25%Coc ROI:38.03%GRM:5.65This represents a purchase at asking price however when I viewed the unit a couple things stood out the attic seemed to have done a little moisture issues so I'm guessing the roof might need replacing, also the tenant in one unit had been therefore 10 years, thus the rental are below market value from comparables a these units rent could conservatively be rented for 600 600 and 525 boosting cf to 383.46, the first unit has lower ceiling also the one tenant who'd been there for 10 years complained of the first unit being occupied by gang bangers who sell drugs out the unit.

My tenant then sent an email directly to the HOA property manager regarding the smoking and they gave her the following response: "We’ve issued a letter to the owner about the excessive smoking.

So taking into account part of that 1200 each month has to go to at least insurance and property taxes your break even time gets extended even further out.If you use a mortgage you are taking money from a bank to buy a property that the tenants will then pay off the mortgage.Another way of looking at this:Lets say all things are equal and you end up holding this property for 30 years and you never have a single expense and you pocket all the cash:A 30 mortgage at 5% with 30k down will cost you $483 per month for 360 monthsso if you pocket the excess each month you will have (1200-483)=717 per month x by 360 months gets you $258,000 for only a 30k investmentnow take that number and multiply by 4 because with 30k down you can buy 4 properties and you have $1,032,480so 120K = $1,032480Your way will pocket 1200 per month for 360 months = $432,000so 120k=$432,000 at the end of 30 yearsnow of course there are extra costs included with the above calculations and thats where owning multiple properties spreads out your risk.  

One we expect to return in excess of 100% within five years, the other 70% within three. 

If the assumption is rust, then you can only conclude that it is the combination of metal and water(moisture).

Excessive snow can cause ice damming at the low eaves and valley flashing that will cause leaking. 

After they're out you'll likely have to sue for damages in excess of the security deposit, which will cost in legal fees and be hard to collect on.Sorry to be the bearer of bad news but you'll need to be diligent in documenting the condition of the apartment after the move-out, and I hope you have a detailed move-in report as well to prove the condition previous to their tenancy.