We have 3 Catalyst 2950-48 switches and each is acting more as a hub than a switch (all traffic can be seen on all ports). My familiarity with this usually indicates that the mac table is full and therefore the switch is dropping back into "hub" mode to ensure delivery of the packets. However, the most MAC addresses I've seen in the switch tables are 97. There are entries for the src and dst MACs in question within these tables so these switches know these addresses.
As an example, please reference the attanced image file. A firewall is logging syslog data to a host in switch A (sw-a). It is from a 192.168.102.x address to a 192.168.101.x address. A host on switch B (sw-b) sees this traffic. This host is in the 192.168.101.x network and is in an access mode switch port. The switch port that the host is connected to is not configured to monitor.