When it's too cold/rainy to go out to the garden with my coffee grounds or even to toss them off the edge of the deck, I'll empty them into indoor potted plants. I haven't tried it with succulents, but anything else seems like fair game. I usually add it like a mulch in larger containers. I have not noticed any issues with either fungal infections or insect pests -- on the contrary, coffee grounds seem to discourage fungus gnats.
