I had a house built 4 years ago shortly after moving in I noticed a bad smell coming from hallway downstairs below our washer and dryer next to a room that holds our lower level hot water heater the smell is not there all the time I can't seem to find a pattern when it appears (ie during washer or when heat is on etc.) I poured bleach down my daughters tub due to a clog and the chlorine smell was very noticeable in the smelly area downstairs and the tub is upstairs.

Sounds like you have some kind of breach or opening into the sewer line, maybe a dried out trap. Are there any floor drains in the area, add water to each of them to replenish the traps water.