Hi Alan,
Do you have separate websites for your businesses? Do you have separate email accounts for your businesses? Do you keep your raw meat separate from your vegetables in the fridge? Do you mix vodka and beer (OK that one is actually not bad) etc...
You definitely need separate accounts for each type of business. When you start following a blog, facebook page, twitter user, etc... let's say about cars and all of a sudden you start seeing information about baby products you start to wonder what's going on?
A. maybe a mistake was made ( if its a 1 time thing)
B. the author has gone mad and trying to solicit non related products
C. the author looses authority and trust on the subject and you start loosing followers and possibly gain negative reactions
I know its hard and extra work but unless you have related businesses like cars and tires or parts you need to separate them and have an individual account for each type of business.
Sorry didn't mean to be rude!