Gcsk your question is very good. I can't say that the value is going to decrease because the unit is rented out, but if more than 50% of the building is NON OWNER OCCUPPIED (NOO)it may be very difficult, even impossible for a buyer or an owner to get a mortgage loan. Fifty (50%) percent of all loans for purchases are FHA and that percentage is higher for condos (Speculation defaults by investors has Fannie & Freddie shying away from condos)and unless the complex is FHA approved, it won't pass a spot approval with a 50% non owner occupancy rate.
So it may be assumed that a condo complex with a high rental rate (NOO) may end up decreasing in value becuase mortgage loans for the complax may be difficult to come by.

Not at first. It really depends on the tenant and if they can care for it. As far as condos that are 50% tenent occupied there certainly is a devaluing of value. It also may be dificult for an owner occupant to recieve a mortgage because of it's status with many mortgage guidelines that will not fnance a condo complex that is more than 20% investor owned.