I think part of the reason BWML get bad press is their business orientated manner - by which I mean they chase money!
Recently BWML (a wholly owned business subsidiary of CRT) fell foul of the feelings that CRT is a charity and should be charitable to all and therefore never seek to enforce its rules. On this occasion they served notice to terminate the contract with a boat owner who had failed to pay their required fees and had been (in BWML's view) objectionable in their manner. As the boater lived aboard and suffered a 'vulnerability' BMWL were immediately branded unreasonable and trying to drive people away from their home, etc, etc,
BWML suffer from being 'troubled' by communication, they aren't good at putting their side (I have received letters that bordered on aggressive rudeness, but I am assured that was not the intent rather it is the manner of the author) and seem to charge into things without feeling their way. That is OK, but can make them appear brusque rather just business-like. They also seem saddled with standing, inherited terms and have failed to write a full and sensible set that they can apply effectively (a bit like various CRT elements). One issue might be trying to apply one set of rules to all 20+ sites which will never work.
Some other points people have mentioned, I think, would be they're expensive, they're growing, their upper management is 'interesting' and they skew the market for various reasons (including not having to pay the NAA - an accounting exercise, but with customer money).
I'm generally happy (if poor) at Apsley.