But actually Crestwood, like a lot of MLPs, is trying to get bigger through mergers so it can improve its asset quality and thereby boost its credit rating.

FORBES: Energy MLPs acquire so they can borrow cheaply... and do more deals

The rating agencies say that the deteriorating credit quality of those trying to finance adventurous takeovers could spell trouble.

ECONOMIST: Corporate debt

We could ask the rating agencies to give up attempting to produce absolute measures of credit quality and instead focus on providing only relative measures.

FORBES: Rethinking Credit Ratings

Given the rating, some investors might assume Sam Rayburn is a lower-quality credit.

FORBES: Muni Bond Manager's Journal: Looking For Real Value

The investors are likely to pull the raw information about a borrower, roll up their sleeves, and analyze the credit quality themselves, either as a primary decision-making tool, or as a double-check on the rating.

FORBES: Credit Ratings and the Fiscal Cliff