They still work. Just be sure to use one with recommendations, do not use a mixer that you cannot find anything about. Your crypto is being mixed with others and you receive a batch of different crypto than the ones you send to the mixer. The only thing is that virtually everyone that uses mixers needs to "clean" their crypto. That means that the crypto you eventually receive is not really "clean" but simply different than the ones you had before. So while they still work it is not fully bullet-proof for having completely clean crypto.