Eh depends on your network hardware and LAN environment.
Usually on wired links you'd expect very low errors and very low dropped packets.
On wireless links you'd expect relatively low errors / dropped packets, but probably not zero, maybe well under 1% of your overall traffic if you were sending reasonable amounts of traffic on an ongoing basis.
On wired links check for autonegotiation or parameter setting problems between your hub/switch and your NICs, things like duplex incompatibilities, 100/1000 specific problems, etc.
Figure out whether your particular firewall or vlan policies are in any way contributing to the "drop" / "error" / "reject" type statistics that worry you, and understand whether it is OK / GOOD that it is dropping / rejecting certain packets.
Check your VLAN and gigabit ethernet JUMBO FRAME settings and be sure that all the nodes on your LAN that intercommunicate have compatible MTU / VLAN / JUMBO FRAME parameters so a packet that is "good" relative to the sender isn't invalid relative to some set of receivers.
[root@q6 html]# netstat -i
Kernel Interface table
Iface MTU Met RX-OK RX-ERR RX-DRP RX-OVR TX-OK TX-ERR TX-DRP TX-OVR Flg
eth0 1500 0 919070 0 0 0 1158916 0 0 0 BMRU
lo 16436 0 22947 0 0 0 22947 0 0 0 LRU
virbr0 1500 0 0 0 0 0 159 0 0 0 BMRU