Well you should be able to find them on your network just do a nbtstat -A to the Ips and that should give you the hostname.
They are clearly clients, looking for those devices. I guest printers from the MFC in their name.
As to such problems on a guest vlan - their broadcasts would be limited to your guest vlan, so not sure how it would be a problem?
As to periodically? That 192.168.0.175 box really wants to find that printer, the is broadcasting every half second or so for it ;)
If I were you I would spend some time watching your broadcast traffic and cleaning up - if they are looking for something that does not exist fix the client so he has the new name, or remove the old device from his setup. if your seeing broadcast for stuff that answers - look to why it got all the way to broadcasting for it, broadcasting is normally last method.
Should look to host, lmhost first then dns, then if node type is hybrid it would do lookup to wins if your running it then finally broadcast for the name. So fix your name resolution, are clients/printers not registering themselves in dns? Are they dhcp or static - pretty much any device on your network that would ever be accessed should be in dns. And while your at it get your reverse zones setup as well, so you can just query PTR for 192.168.0.175 and know what its hostname is, etc.