Here is a simple way to think about what might alter the expected branching ratio products from (say) d+d fusion to result in the "little or no high energy products" characteristic of most LENR experiments otherwise claimed positive.
http://sjbyrnes.com/cf/branching-ratio-collective-effects/
If you agree with this argument it rules out a number of theories simply - and on grounds that are very fundamental.
It is an application of the "nuclear reactions are hard to influence because they occur at such very short time and space scales" principle.
Decay reactions of nearly stable nuclei have long time scales, but all have small space scales hence not much can get close, just electric and magnetic fields
Most fusion reactions also have very short time scales because the intermediate fused particle, carrying lots of extra energy from the fusion, has very short lifetime.
Short reaction time => limited number of things can influence the reaction (from relativity).
So: who agrees with it? Who disagrees (and if so what is the loophole). Who reckons their favourite fusion happens theory avoids it?