I totally hear you, it may not feel good, but I think it feels better to have tenants paying on time with no vacancies. It's a personal call, you could make things awkward by questioning them, especially when you don't have any apparent authority to do so, unless of course they are causing damage. Or, talking to them could work wonders and they completely change their ways, sometimes people just need a little push to make a change. If you think the cleanup costs will be higher as a result, such as to remove smells/stains, you could tell them.
I had tenants a few years back that were incredibly dirty. It literally smelled like garbage when I walked into the place, the toilets had um stuff...running down the side, couldn't see the countertop cuz of trash, the list goes on, it was awful really, but they paid on time. I knew I would have to keep more of their deposit to clean the place, which I did, but I could have told them this while they were still living there, to hopefully help curb their cleanliness. But then of course I run the risk of them marginally cleaning up, and then expecting me to not charge extra for cleaning. At the end of the day I didn't say anything until they moved out and they were ok with the extra costs. It was hard for my wife to see it this dirty, because it was our first home we lived in after we got married and was on the nicer/newer side, but I told her the same stuff I'm writing here, there isn't much strong-arming I think you can do, but sometimes it doesn't hurt to ask them.