Liabilities of service receiver being company.

Registartion under service tax is a responsibility of service provider. If Service provider do not registered himself (if he is liable to be regsitered), then, service receiver can't be held responsible. There is no risk or non-compliance at the end of service receiver

while service tax audit on service receiver being company, is there any audit objection raised by service tax auditor? second any harm and problems by issuing work orders to such service provider to service receiver? by inserting notwithstanding clause "any future liabilities with respect to taxes towards this work order,service provider is solely responsible and born by himself only and not of service receiver" is there any problem.?

thank you for your good advise. please clarify the above issue with provisions and if any case laws please mention.