I worked at sea for over 8 years in the international salvage industry, 5 of those years as ships captain and salvage master.
The wikipedia listing on salvors and the various different types of salvage is pretty accurate:
http://en.wikipedia.org/wiki/Marine_salvage
Particular to this discussion is the issue of consent (contract salvage vs. emergency salvage) offshore and protected waters is also a key factor.
My personal opinion is, these ham & egg franchise tow operations are absurd and are operating in a marine version of the old ambulance chaser metaphor, taking advantage of laws that were never meant to apply to small inland recreational situations and counting on owners and insurance companies choosing to pay as opposed to fighting a court case to assert their rights.
You have guys with six pack or 50 or 100 ton inland tickets with a tow certificate and no real expertise running around looking to make a buck by abusing ceturies old laws meant to create order in international commercial shipping salvage situations.
It is the type of thing that an industry group ought to take up as an issue but given the fact that the largest marine representative organization (Boat US) makes most of its revenue from tow contracts and franchise revenue from these guys, it isnt likely that they will weigh in on behalf of the victims of these scams.
Obviously there are good and bad operators but even good ones are choosing to be professionally associated with an indusry that is operating in a legal grey area. The bottom line is that any true emergency which would qualify as elevating the situation to "lloyds open form" should be handled by either the coast guard or trained professional salvors...not a putz with a 50 ton ticket, a skiff with a little light on top and a dream of striking it rich with the slavage of our yachts.
The one thing I would recomend everyone keep in mind is the consent issue. If you are in need of assistance, BEFORE granting consent to a tow operator you need to memorialize the fact that you want to engage in a CONTRACT tow. If they try and board your vessel it is important that you do not grant permission until the salvage method is clearly determined, either in writing or at least take out your cell phone and record the conversation with the video function.
If they try and board your vessel with that idiotic quasi-official, volunteer firefighter pushy-ness that they seem to enjoy, tell them to get off your boat immediately or you will press charges. If they dont comply get on the radio with the CG, who records these calls and inform them that you have a tow operator who does NOT have permission to be aboard and you need assitance.
Unfortunately the US Coast guard has looked the other way on this issue as a way to get out from under all but emergency situations but that calll will get them motivated and most likely the tow guy will start behaving out of fear of losing his ticket.