I have a few solutions here and there that seem to help. First I let customers know that I can keep their names anonymous and always make a point of asking them about this. Occasionally I've been able to offer "clean" or at least "vanilla" versions of the commission that at least allows me something I could display. If neither option is viable I usually ask for an extra fee to keep the commission "private" agreeing to it never seeing the light of day, basically.
Annoyingly one or two have asked me to keep trades private. Something I've been repeatedly refusing to do as it usually involves me doing free art, and then doing free art that I don't have rights to!