I have caulked a lot of bathrooms. If you go over anything this is slightly moldy, it will fail not too long down the road. If the caulking is good and very clean and looks nice, then you can but right up to it or even go over it a ways.
It is always asking for trouble, in my book, to go over old caulking if doing more than just a small repair or touch up.
I also, once the old caulking is removed, spray a bleach solution on the areas to be caulked then rinse with water, let dry, then caulk. I've never had any failures on the jobs that I've done this to go back and redo any of the job.
One thing I do when the caulking has to be perfect, I use blue tape on both sides of what is to be caulked, smooth out the caulking exactly how I want then remove the tape. If you spaced the tape right there will be a perfect line and no ridge on the edges of the caulking. I usually do this at the tube to floor transition when someone left a larger than normal gap at the flooring to tub transition. Around the wall to tub I usually don't.
Just my two cents!
And thanks for the new recipe Cynthia and Vaughn! I never thought of using caulking on my french fries before! Good old stick to your ribs food!
That's not even a smile! That's just a bunch of teeth playing with my mind!