Depends on my mood. At the time of this writing, two on the front page of a site is too many. Site claims graphics as their own, even when they did not create them. Fiends and scalawags.
Site is too slow.
Now, I am willing to wait a long long time for graphic sites, I know they're going to be slow. If a site is slow, I'll even check back another time to make sure it wasn't a fluke. But the occasional site, that won't load something in under two minutes does not make it to the database. Sites that create graphics for web site use and create graphics far too heavy for reasonable use on the web. 70k is too big a file for a background.