Has anyone tried these SnugPlugs?

A high quality AC outlet grips much better , I bought the $200 Furutech  outlet very good and sonically better but take a full 200 hours to runin.

An electrician friend of mine said that they will ruin the outlet. Over time the contacts writhing the outlet will be pushed back and loose the ability to hold a plug with or without them. For 3-5.00 it’s best to replace the outlet. If it’s a heavy use outlet buy a better brand, e.g. Hubble

I would want to know how they change the sound before I decided on using them.

I think the concept is prolonging use of an already ruined outlet

Go for a better outlet.  I noticed a bigger improvement in sound over new a/c power cords.