Grammatically it's correct but you would never use "spotless" in this context. "Spotless" means that something is totally clean and without blemish, so it's normally used for a bathroom, kitchen, article of clothing or something like that. I think here, you are talking about tidiness, not cleanliness, so it's the wrong word to use; the outdoors is never clean, not in that sense, as there are always birds, wild animals and insects about, doing whatever they do!

Hi, yes use it in this context, practically it's hard to keep the whole of the environment spotless, so you could say "preserving the environment should be encouraged by minimizing the litter and keeping out surroundings spotless"

Hi, There's a mistake in your question. There isn't any subject after the verb can. This should read: Can we use ... (Or, some other subject.) Cheers

Yep, that is a correct sentence!