If you are doing sperm-meets-egg plan, you have to SWI five days running and that takes quite some doing, IME, even with lots of natural lubrication.
We tried both Conceive Plus and Pre-Seed and both STINK. I felt incredibly self-conscious although DH pretended it wasn't that bad. It was.
Also, it's very hard to judge the right amount needed (because this, er, varies) and if you use too much, it is impossible to get the big O.
They're also very expensive and I've since heard that both coconut oil and Canola (brand name) oil are equally suitable and about a million times cheaper.
We'd have carried on using them, however, because KY is spermicidal. Except my HSG revealed I have blocked tubes because of fibroids and adhesions, so now I need a hysteroscopy, not slippery shagging 