It is possible to create a rule without a quality dimension and it can be submitted for approval , but as soon as you click the refresh , its no longer visible under the rule menu. I'm not sure if SAP has already addressed this issue in SP6 which was released late Nov '15.
To find out such rules without a dimension associated with it , you need to query the repository metadata tables MMT_Rule and MMT_Custom_Field_Value
select * from ( select distinct ,t1.business_name as Rule_name ,t2.value as Quality_dimension ,t1.effective_dt as Rule_created_Date from MMT_Rule t1 left join MMT_Custom_Field_Value t2 on t1.rule_id = t2.[object_id] and t2.is_current_Version = 'Y' and t2.field_name = 'CA.rule dimension' ) T where Quality_dimension is null
