I pulled a few lisitngs from Trulia and compared the data there to the info on the tax data source that we use. The data was consistent in my sampling.
Trulia might be using a different source for data transmission of the assessor data in GA than Jenny Pruitt. That is one possibility.
Here's another, and I have seen this in our area. The lot size is a trapezoid. The front width is 100' and the back width is 80'. One data system calculated square footage using the width of 100, and another averaged the front and back numbers to 90' wide and calculated the square footage of the lot.
Another possibility is that the data was input into the tax assessor records incorrectly. I have read the data from a database that states a lot is 50' wide, and when I look at the tax map, the map has 59' on it. The data was input into a database system from individuals looking at the tax map. With a wonderfully accurate diligent perfromance record, there are still going to be errors.
An agent can pull the tax maps, cross verify the data entered, or refer to a survey if available from the seller.
In a purchase contract, you will obtain your own survey for validation of lot size also.
Here is my priority evaluation for data on lot size: 1) The survey 2) Tax Map 3) Tax database with text numbers
I know the inconsistency of data can be frustrating. This is but just one example of things that agents do behind the scenes when representing buyers and sellers. So often, we resolve discrepancies, validate info, and make corrections without ever mentioning it to our clients.
Point out any discrepancies to your buyer agent and ask him/her to do their homework for you.