Googles response from the server is in UTF-8 but some columns maintain their original charset, so your Umlauts or other special charaters will look defect ( e.g. campaignName).
To fix it, you can use TO_CHARS and TO_BYTES.
In Germany these columns are often encoded in windows-1252, so your view can be fixed like in this Example:
create view views.adwords_clicks_per_campaignAS select adwords.customer_id.customerId ,campaignId ,CAST( TO_CHARS( TO_BYTES( "campaignName", 'windows-1252' ) , 'UTF-8' ) as string ) as "campaignName" ,accountId ,clicks from adwords.customer_id ,table ( exec "adwords"."getCAMPAIGN_PERFORMANCE_REPORT" ( adwords.customer_id.customerId ,'2013-01-01' ,curdate ( ) ,'AccountId,Clicks,campaignId,campaignName' ) ) a;;