Or do they usually sit tight until they get an agent to list it on the market for full retail value? 

There's usually a clear winner after you do this.Good Luck!

It usually depends on how property taxes are collected by the city/town.

HUD deals seem to be listed (usually owner occupant, non profit and government agencies for some period of time depending on the "insurability" of it) on the MLS.

i'm looking for the forum's advice on the most efficient/effective way of weeding out properties. i'll be living in the property for at least a year. while i live there, i'll be living in it (so property can't be a complete rehab), fixing or improving the property, and then either flipping or renting out the property. i've looked at about 18 properties the past 3 weekends (i just started 3 weeks ago). the 18 properties were chosen based on 2 broad criteria: 1) based on pictures, description, and google street view, choose properties close to the metra (in illinois), in a location with a great high school (>=8 score), and in nice(r) neighborhood.2) look at zillow for an idea on property values in the neighborhood so that i'm not buying one of the most expensive houses in the neighborhood. if i feel the house i'm looking at is somewhat undervalued because it needs work and there's some room for me to flip, then house passes.this criteria has helped me weed out 100's of properties, but takes me a bit of time.i'm curious, is this a good start or are there other ways that the full time/professional investors use?

And at least once a year usually during the summer months I make sure I'm doing maintenance on the units.

It basically made it so the rent was always paid before the 15th lol, have one tenant that still pays as late as possible, usually on the 13-14th.

They are usually pretty easy to find online.

Over the long 20+ year pull with dividends reinvested an SP 500 index fund will return ABOUT 10% so when I see things at least in the low teens I usually start nodding my head.  

Additionally, there should be a written lease with the usual and customary lease provisions.