Some brothers feel it is wrong and unclean to baptize in a bathtub? What do you think?

We must ask, does the Bible state where someone ought to be baptized? If yes, we must follow instructions. If not, this is a matter of opinion. The only published opinions on this matter of which I am aware are found in the 2nd century Didache. There the first choice is cool, running water. But the Didache is not inspired scripture. It is the word of man.

Accordingly, this must remain an area of preference.