What are the problems associated with Payment Delay for Purchase Bills? How far it affects the reputation of the company?

As you already mentioned in your question reputation is the most important thing which is at stake. Sometimes company may suffer huge production losses due to non-availability of raw-material due to non-payment to suppliers. Production costs and other expenses may increase as a result of ineligibility of the company to claim settlement and other discounts due to delayed payment. Sometimes even suppliers may refuse to grant credit in futrue and may insist on up-front cash payment for all supplies.

The Delay in payments normally due to the delay in recovery from the clients and simultaneously the company is not able to meet its short term liabilities. Other delay may be due to improper invoices received from the service providers. Like Proper Goods received vouchers & delivery notes backed by detailed invoice, proper timesheets and invoice with signed contracts from both the contractor and contractee.

Delay for paid  Purchase Bills mean delay of product sources "material"

mean

*- lose time 

* bad reputation

*- lose suppliers

*- lose customers

*- lose competition 

*- lose money

I agree with all

First delay of payments have many reasons ( Cash Flow / Collections Down / New investments / etc..)

Which lead to not pay on time for most of the companies but a little of companies runs reports of delaying of payment but I know some of them make meeting group for not reaching payments on time less then95 % . finally I think cash flow is first step to let your company the physical status it can move on. 

The delay for payment should be Invoice is on Hold due to requester hold and Supplier hold