I don't want to use an absolute but at least in Texas and from what I can tell everywhere else (but maybe there is an outlier) you do not disclose that a home is a modular, same as you don't disclose the build method used in any stick build home or if certain parts are add-ons or anything. Modular is simply a tactical decision.
Eric and I have been incidentally tag teaming these modular posts recently, he has designed and discusses that aspect while I have bought 1 this far (FYI it was not disclosed as a modular, appraised in the same manner as a stick build as there is nothing on the form for any indication, and neither my property manager, nor the bank, nor my agent had any idea). I knew what it was because I noticed the way this older modular (early 2000's) managed the seam. In the newest ones you shouldn't be able to tell at all unless you take the walls apart
Currently I am researching duplex modulars. I have found two builders that have variant quality.
One is at $100 per square foot including build and delivery, the layout and finishings are very nice. The company is "Modular Homes of America".
Another is a company that mostly builds manufactures (mobile) homes but can also build to Modular standards. These guys have a duplex that goes for $60 per square foot. The finishings are not as nice and the footprint is a little smaller.
Point to keep in mind is this does not include land, land prep, foundation, driveway, utilities, management. All of that can add another $60- $100 per square foot.
My goal is to get really good at the financing, land aquisition, and land prep and have the home built and delivered, and then refinance out.