Big gray wall syndrome
The Big Gray Wall Syndrome, also known as simply BGWS, is a type of building style most castle builders try to avoid. MOCs that have large expanses of plain, featureless gray castle walls are usually identified as having this "syndrome." Bruce Hietbrink coined the term on Classic-Castle.com.
The same phenomenon of featureless walls occurs in other themes such as Town (though it is not usually given this name). Most builders try to avoid it. Large expanses of featureless studded areas produced by many plates are often avoided, but not as strongly.