Learn English – How to deal with quoting a grammatical error

I agree with Peter Shor's answer, however, looking at this phrase in the COCA corpus, there seems to be an exception that is most prevalent in spoken English where ought not be is a frequent although still less common alternative to ought not to be. For example:

...one could argue then that President Bush ought not be succeeding.

2005 Tavis Smiley, PBS

Searching a selection of classic texts I found no instances of ought not be, and British English also appears to reject omission of the 'to' in negative ought. So I would tentatively conclude that this is a development in contemporary American English.

1. Your understanding of the sentence is correct—it means that Harry's room is the one on the right.

2. It is grammatically acceptable, but a sentence that is grammatically correct is not necessarily meaningful. In this case, however, it is understandable, but your phrasing of the sentence would be the complete form.

3. Personally, I would not use this construction; it's a rather unusual one. Using this sentence might imply familiarity or distraction, depending on the observer.

4. I can think of several, but they are not in the same style as your quote. Most sentence of this type, such as You are my doll, use meanings that have become embedded in the language and are reported on in dictionaries. Sentences like those in your quote are extremely unlikely to be encountered and I would not recommend using them.