Do they work? That question gets asked a lot in various forums (see here and here). There is no clear answers if they really do help pr not. Some anecdotal claims are that they do help and some are that they do not help. The published research only shows a small change in the angle of the toe that may not be sustained in the longer term.
There is a lot of marketing hype around them. They will not make bunions go away. At best they appear to improve the angle of the big toe a little, but needs to be worn every night for a month or so to get that small improvement. There is no harm in trying the bunion correctors, as that small improvement may make quite a difference to the symptoms.