I use it all the time, but reading about it here I admit it could be slightly ambiguous and confusing. I'll try to use the full Visual Contact in the future. Even Visual would be better since it can't be confused with much anything else.
Looking is much better than Roger, IMHO. Don't care what the rules say - clarity is paramount. Looking is a direct acknowledgement of traffic, whereas Roger could be agreeing to anything said up that point.