First of all, I would like to say this is a very common subject when screening for a new tenant.

This is common and can sometimes be very difficult to detect, even for seasoned pro's.

Common bleach solution does well,  50/50 mop the floor, let stand several hours and then rinse with clear water (you said you didn't care re the finish). 

A common one for the brand new buy and hold landlord with their first rental unit is what I call hgtv syndrome or simply over-remodeling.

The plumber informed me that the clog was due to "user error.""

just depends on your market cost of capital and how long it will take.. those are very common numbers for house flipping.

@Mark NeigerHard to give specific advice on strategies without knowing your resources, time availability, and market.Poke around on BP for a while as this question has been asked many times.The only common denominator I've found with all methods is patience and persistence.Good luck.

The boat slips are rented seasonally, paid up front, and currently generates $2,000/month (when averaged over the year).Total monthly income: $11,250 ($135,000/year)Expenses run very low, from what we can tell, listed annual expense:RE Taxes :12,000Insurance: $6,500Water + Common Electric: $3,000 (heat and hot water is paid by tenant)Maintenance + Repairs: $2,000Management: $10,000If we do 40% down ($700,000) and finance $1,050,000 @ 4% over 15 years: $93,300.Add for vacancy, misc, etc...  

We have helped many investors set it up to remove the common mistakes people make on the platform.

The control board should be able to tell if the temperature sensor is unplugged or broken, so if you aren't getting any error codes on the display, the sensor is probably OK.