Yes and no – there usually needs to be a gimmick to make it worth while – a general book is normally a huge topic requiring a specialist research and writing team that takes years to put together and consists of either easily verifiable info (in which case what was the point) – or hard to verify info (in which case is the publisher taking a risk publishing it).
Reference books are always of interest to us – we are happy to look at them or discuss ideas – so don’t be too discouraged – but the subject area needs to be one that will have appeal to several different markets, or it won’t be commercially viable.