This walking liberty half dollar looks garish to me. http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=140359827058&ssPageName=STRK:MEWAX:IT Isn't it too toned to be appealing?
Depends on who you ask. To me there is too much toning whenever you start seeing rainbow type toning. Just my opinion.
Toning is like ice cream, except there are more flavors of toning. What I mean is some people like this flavor and some that flavor. I call it the chocolate and vanilla syndrome. But to answer your question, yes there is such a thing as too much toning. Ignoring the coin you pictured, what I am talking about is toning that has turned very dark. It can vary from dark blues & browns to black. And toning like this has progressed to the point that it is, or has become, corrosion. Corrosion to the point that it is pitting the metal and literally eating away at the coin.
For almost all buyers, at a certain point, a coin is too heavily toned to be desirable. Different people have different preferences and draw the line in different places, however. The coin you linked is a horrible artificial toning job. It's not that it's "too toned" but rather, it is completely unnatural looking.
I know little about toning but I've noticted a few times when I've accidently left coins in my pants pockets and washed them, sometimes the coines come out toned,just an observation : )
I'd say it must just be a matter of taste. I don't collect toned coins, but if I ever happened into one in change that looked cool, I'd probably keep it. I like looking at them if they're cool looking, real or fake, but I'd never find myself purchasing one.