Motley Fool's Mike King on CLH, page-30

Personally I find the ratios useful to highlight the obvious differences in approach and thus to then normalise performance between them. Thus they can help you steer clear of making value decisions solely on what may be considered non-comparable numbers like p/e, ROE, amortisation etc between these entities. E.g if you amortised all your assets in past periods then equity will be lower, so when the cash still rolls in earnings and thus ROE is obviously going to drift higher. It forces one to look more under the hood so to speak as it is clear it's relatively easy to manipulate/big bath account earnings for an extended period of time. Cash flows lie less easily and thus why my more fulsome assessments focus on deeper analysis of these (although channel stuffing can be used to mask shorter term collection issues - e.g. Pay me 50% today on 29 June and I'll let you off the rest but it's a one time deal and you have to do it now...)

Another example the rise in CCP P/E ratio makes it look like they are getting expensive, but a closer look might have one wondering if they actually still represent reasonably good value (not making that call necessarily, more to illustrate the point).

I find the ratios useful, but as noted for high level assessments only, not for an ultimate investment decision.

DYOR