I wrote only yesterday about the importance of keeping your data consistent across the web and website with your Google Places entry.
Today there pops up the usual problem of shared ownership and root named businesses operating cheek by jowl.
Less of an issue now Google are manually separating merged Places listings BUT that does not fix the lower ranking problems.
By not having clear separation across the web of the two entities data Googles ranking algorithm will give each a lower score because of conflicting data. So just because Google can wave a magic hand over the keyboard, its not that magic.
Also as Jim pointed out salesmen swapping entities need to be carefully managed from a data point of view. Perhaps keep their transient details out of your web listings.