They don't work, simple as that. I've read a more than a few reviews and as Cindy says they are nowhere near powerful enough, certainly not enough to make any difference to a typical male beard. They wouldn't dare sell something powerful enough because people would be burning themselves left right and centre and suing the manufacturer almost as fast. Save your money. When you consider that even a professional unit struggles to get even a % done how could a home unit come anywhere close.
As for recommending tweezing, that's not a good idea either. Tweezing will encourage more hair not get rid of it. Ripping a hair out by the root (tweezing) actually strengthens a follicle most of the time. It causes an increase in blood supply which can also fire up other adjacent follicles and they may start producing hair as well. It may on occasion damage a follicle to a point where it won't grow back but this is the exception not the rule. The only place where tweezing will cause the hair to stop growing is the eyebrows. I don't think anyone knows why for sure but I'm pretty sure I'm right in what I say. There's also a risk of scarring from tweezing and the chance of ingrown's. Tweezing on your face is not a good idea, a lot of electrologists will tell you that tweezed hairs are harder to deal with.... They can certainly be stronger and deeper rooted, this means they need more energy to remove them and destroy the follicle, as you can imagine this translates into more discomfort.
There's no doubt someone going to say "what about waxing, that reduces hair growth" I've read into this as well. The waxing fraternity claim that over time waxing will reduce the amount of hair. Again from what I've read this isn't the case. Over time, considerable time, the amount of hair may well reduce anyway, in the same breath it also might not, everyone's different. The waxers claim this naturally occurring reduction as their own. . When someone is waxed regularly the hair does appear to grow in finer, this isn't the case. What's happening is as the new unshaved hair grows through it appears finer because when it first comes through it is tapered and fine and therefore appears as though it isn't as coarse as could be seen when shaving. Women love this and it keeps them going back for more, it's a nice little money spinner for the salons. Some salons will encourage women to wax their upper lip as well, this isn't a good idea for the client but it does good things for the salon. In time what can and does happen in a lot of cases is that the hairs that have been waxed will strengthen to a point where they will be considerably more noticeable than they were in the beginning. They can end up being too strong for waxing as is the male beard and this allows the salon the opportunity to offer laser or electrolysis and on it goes with tills ringing nicely in the background thank you very much. The salon will just blame hormones or the onset of menopause which might be the case in some instances but they will not have helped matters themselves by ripping the hairs out stimulating blood flow and causing what was just a bit of fluff to transform into some well rooted terminal hair. It's an uncomfortable reality to consider but these smiling well made up ladies want your cash and they're not too bothered about how they get it. Anyone who is waxed regularly is probably familiar with ingrown's, sometimes they end up infected and as a result you end up with a scar or hyper/hypo pigmentation. All in the name of beauty

Sorry if I've droned on Again but some points need a little explaining to get across well. Marks out of ten? ? ?

If I sound a little anti salon I have to admit I am. I'm a terrible skeptic where some of the treatments that they offer are concerned. I hate being scammed or seeing people being scammed and some salons have an arsenal of tools to separate people from their money. You have been warned

It's false smile central