Readability for complex associations

gistfile1.rb

  has_many :performances, :dependent => :destroy

  has_many :keyword_vendor_instances,
           :class_name  => 'Scenario::Keyword::VendorInstance',
           :foreign_key => :ad_group_vendor_instance_id

  has_many :ad_vendor_instances,
           :class_name  => 'Scenario::Ad::VendorInstance',
           :foreign_key => :ad_group_vendor_instance_id


# And not this:

has_many :join_geo_target_scenario_campaign_vendor_instances, :dependent => :destroy,                                            :class_name => 'Join::GeoTargetScenarioCampaignVendorInstance'
  has_many :geo_targets,                                        :through   => :join_geo_target_scenario_campaign_vendor_instances, :conditions => { :join_geo_target_scenario_campaign_vendor_instances => {:exclusive => false} }
  has_many :exclusive_geo_targets,                              :through   => :join_geo_target_scenario_campaign_vendor_instances, :conditions => { :join_geo_target_scenario_campaign_vendor_instances => {:exclusive => true} }, :source => :geo_target