How accurate is Rentometer?

[Jeremy L Moskal]

I am looking at 2 different MFH in my area to purchase for my first investment property.  But I'm having trouble with the huge discrepancy in rent prices to judge them on. The first is a triplex which Rentometer says should rent at 800 per unit. However, they are currently renting at 500 per unit. The second is a duplex which rentometer has at 1100 per unit, but are renting at 750. I've looked on zillow and the cheapest 2 bed 1 bath(which is what the Triplex is) is 750, and the cheapest 3 bed 1 bath(duplex) is 900. Is this a case of landlords just not keeping up with rent inflation or am I missing something as a new investor? Any advice welcome! Thank you!