Gags are an item that is going to appeal to a subset of tickling folks.
For the majority, being able to hear the full effect of the tickling on the lee is very important. This is the majority aspect of the fetish group, and covers most of the factions in it.
But for some, control over a lees ability to express themselves is important and a turn on. For them, gags add an addition aspect of control and power over the lee. Seeing the lee struggle, and the muted sounds is more their focus, rather then a clear hearing of laughter or begging. In short, it's not the sort of reaction that matters to this group, but that the are causing one in toto. In fact, many might find the ungagged lee distracting, and simply wish to work with no 'feedback', and just enjoy the suffering they are inflicting by the muted mews and mffs. The drooling aspect is a turn on to some also, as it's a visible sign of loss of control, and a minor humiliation bump. (Often more then one fetish is active in a person, and they combine into a fetish stew that prompts unique targeted scenarios.)
As with most fetishes there is a power aspect involved. And people fall along that line differently of course, and their tastes are reflected in that. What is important to the Ler, will vary. And the tools they enjoy to use fold around that.
Personally I prefer no gags. I enjoy being able to hear the full effect of my actions.
Myriads
