If you are looking for Blahtown in a state don’t assume that the first place with that name is the actual one you want. There could have been more than one place originally named Blahtown–perhaps a place whose name was changed when it was realized that there was another one in the same state.
There could also be places named “Blah,” “Blahsville,” etc. to which the “Blahtown” reference was actually referring. Blah could also be the name of a political jurisdiction other than a town (perhaps a township) and could even have been an informal area that never warranted an official name.
If you have an idea where “Blahtown” was at but cannot find it, search old newspapers in the area for that name. If it was an informal, but named area, chances are there are some newspaper references to it–if it nothing other than “gossip” columns.