I think the number of messages arent as important as the size.
But if it is many large messages then there is a problem.
A map addon like GuildMap or Cartographer needs to send a lot of messages since you want to know where your guildies are now and not later. But those who write such addons must be concentrating on making the data as small as possible.
Same goes for Threat/Omen. Realtime data, but it should be as small as possible.
So it is important you look at both the number and size in order to determine if it is really "spam" or not.
When I do /script SendAddonMessage("TEST","Testing","GUILD") the counter increases with 11 but nothing is shown in the window. Only "No Data Observed Yet" collecting for x.xx.
I do track everything except battleground.