Caulking is a vital part of keeping water out of the joints around your bathtub, shower pan, backsplash, etc.. It is important for calking to be correctly applied and maintained to avoid moisture damage which can lead to mould. We often see caulking that is mouldy, and overlooked. Mouldy caulking suggests that water is getting in somewhere and staying there, forming mould. Sometimes this the mouldy caulking can be cleaned with bleach and a toothbrush if it is in good shape overall. More often, we see that the caulking has to be cut/scraped away, cleaned with bleach, dried, and reapplied.
We only use top quality 100% silicone caulking. We keep it in stock and have tips and tricks to apply it cleanly and evenly. Once installed, it is good for several years.
We view caulking as cheap insurance against larger problems where water can get in behind tiles and cause expensive damage. We highly recommend that landlords pay close attention to this as you are the one who pays the bill when there are larger problems, not your tenants.
If your caulking looks nasty, it probably is, and should be replaced.