If it is creamy (like a think, white paste or paint) then its the CM before the GOOD, fertile CM. It's still cervical mucas, just not the really good kind. ha!
I know people say the best Cervical Mucas looks like eggwhite or snot. However, if you don't feel it with your fingers and it ends up in your underwear (which happens more frequently because we are going about our day and our underwear are suddenly wet) you can tell if it is the fertile CM by the MARK or SPOT it makes in your undies.
Fertile/eggwhite CM makes a round, wet spot on your undies. When you pee and it comes out into the toilet bowl, it is insoluble and won't just mix in with the water. It will look like a cloudy marble.
I hope that helps.