If a Plugin creates a table with a foreign key into a core table (eg: cm_co_my_plugin:co_person_id), attempting to delete the CO Person will fail because the MyPlugin foreign key still exists and Cake can't/doesn't know to delete the MyPlugin record.

(1) For the most part, the core doesn't know when a Plugin might have a hasOne/hasMany/belongsTo relation. (The exception is for provisioning plugins, which are treated specially in CoProvisioningTargetsController.)

(2) Even if it did, as of Cake v2.0.5 there appears to be a bug/feature that resets any dynamically bound associations (due to a find() called as part of Model/Model.php:delete()).