The comets we have observed via spacecraft, as well as the bits collected by the StarDust mission, agree very well with the "old dirty snowball theory" ... except that they're a bit dirtier than previously thought.
The "solar wind" is quite energetic even at very great distances from the Sun (around the orbital distances of the gas giants). Even so, none of the comets I have observed while at such distances from the Sun do not have "very long twisted tails" at that range.
I haven't viewed more than about 100 or so via SOHO "movies", during their perigee passes. Only a very few of them tend to lose their tails at perigee (probably because perigee distances are still quite large (not counting the so-called "sun divers", of course.
While I'm not an expert on comets, per se, I do study meteoritics. The difference between comets, asteroid, and meteoroids seems now not to be so large as was thought only a few decades ago. I am not aware of any mechanism by which electromagnetic or electrostatic fields can arise and persist in these bodies, except by their passage through the solar wind and solar or planetary magnetic fields. There is enough nickel-iron in these bodies to support some level of induction during such passage, but I'm not aware of such fields being indigenous to the bodies, themselves. Of course, the problem with studying such fields in meteorites is that meteorites (being On the Earth) are within a considerable magnetic field while being studied.
In induced electromagnetic field that is carried along with such a body in orbit around the Sun should have an effect on particles streaming from it (as those ejected in the form of a tail), but I know of no study that shows such fields being strong enough to create cometary tails.
Sublimation, however, can be quite dramatic even at very low differentials of heat and pressure -- especially when you consider that comets travel at cosmic velocities when approaching or receding from the Sun.
The universe is not only stranger than we imagine, it's stranger than we CAN imagine. --- JBS Haldane
Come visit me at Comanche Springs Astronomy Campus (we're on Google Maps) in Texas.