While it’s understandable to want a quick fix, painting over tile adhesive is not typically recommended, as it may not adhere well or could peel over time, especially in a wet environment like a shower. Instead, consider these options:
1. **Remove the Adhesive**: If possible, carefully scrape or sand the excess adhesive from the grout lines. This will provide a cleaner look and prevent future issues. Be cautious not to damage the tiles or grout.
2. **Use a Grout Colorant**: If the adhesive is only visible in the grout lines, a grout colorant can be a great solution. These products are designed for wet areas and can help mask the grey adhesive while also sealing the grout.
3. **Regrouting**: If the adhesive is widespread, you might want to consider regrouting the affected areas. This involves removing the old grout and applying a new, matching color.
If you decide to hire a professional, expect to pay between $200 and $600 for regrouting, depending on your location and the extent of the work.
As a next step, you may want to get 2–3 local quotes on Handyman.com to explore your options.
— Assisted answer