Can being constantly surrounded by ugly things and people ruin own's sense of
Let's start with the phrase "ruin one's own sense of the aesthetic." There might be different ways to interpret that, but the reading that first occurred to me was something like "undermine one's ability to appreciate things aesthetically" or perhaps "undermine one's ability to make sound aesthetic judgements."
In either case, the question isn't just philosophical. It's partly a matter of what the actual psychological effects of being surrounded by beautiful—or ugly—things actually is. And although we might have guesses about the answers, our guesses might not be good ones.
With due regard for the fact that philosophers can't really answer the question, however, we can still ask some rather more conceptual questions. What about aesthetic value might suggest that being surrounded by ugly things could ruin our aesthetic sensibilities? One possible reason is that if we're surrounded by ugliness, we may have trouble noticing things that are beautiful or in some other way aesthetically rewarding. However, it's at least possible that if we only rarely encounter beauty, we might be more attuned to it. Which, if either, of these is true isn't something we can answer by guessing.
A related possibility: it can take time, effort and attention to appreciate the aesthetic value of some things. It could be that if our spirits are beaten down by ugliness, our capacity for certain kinds of subtle perception might be damaged. But again: all we've done is identify a possibility; whether things really work this way is another matter.
At first your second question might seem odd: we might wonder how being surrounded by beauty could ruin our aesthetic sensibility. But it's not too hard to imagine some ways this could work. Perhaps if we're constantly surrounded by beauty we become insensitive to it—we stop noticing. Another possibility: not everything that's aesthetically valuable is beautiful. For example: there's music that I value highly, but that doesn't seem beautiful. It's too fierce for that. It could be that an overdose of beauty makes it hard to appreciate other kinds of aesthetic value.
Though I'll now sound like a broken record, a philosopher can't tell us which of these speculations is correct. But it does seem to me that there's some potentially interesting and fruitful research that might come out of combining methods in experimental psychology with the insights of artists, appreciators of art, and aestheticians. I'd be very curious to see what we'd actually uncover if we pursued this sort of multi-disciplinary investigation.