Renderotica

What I'd really like to see is a way to put streaks or spots of cum or piss on outer clothing or on the body, for people standing up or cloe to standing up. For those "Oh no, I've wet myself" or " i couldn't stop from cumming!" -type situations. Like you do. Stains or blobby/drippy cum is good. 

There are a few things that let you put dforce cum on the body or clothing, but those only seem to work well for someone laying down because it drapes. 

Since I see nothing already for such a product, I suspect the answer is 'it's impossible'. 

The problem with stains on 3D clothing is actually not that simple. The dForce solution isn't bad (I did a project with it a long time ago). Advantage: you can get all kinds of things to spill on it :D

The props suggested by DBXXX are also great and have the big advantage of being generation (Genesis) independent.

Another option would be decals. In theory, you could also use these to stain all kinds of things. The problem with decals, however, is their use (and problems with GeoGrafts). I also have an older project on this.

Another option is 3D clothing that is stained from the outset (i.e., as a material preset) or that can be stained via GeoShell.

Personally, I'm currently focusing on the latter option, as it's very easy for users and gives me 100% control over the materials. A new project is currently in the works.

Take a look at my shop (not to buy anything, just for inspiration). I usually have free readmes with my projects that explain how to use them.