You do have to be a little careful sometimes recording in bathrooms because the room may have some nasty resonances and make some notes jump out more than others etc. It is a good idea to look at the dimensions of a bathroom and plug those values into the formula that relates speed of sound to wavelength and frequency.
eg Freq = Speed of sound/ length
Speed of sound can be feet per sec eg 1120 ft/s or 344 metres/second.
Hard surfaces in a bathroom will encourage sound to bounce off walls with great vigour. One of my bathroom dimensions is 2.2 metres which equates to a frequency of 156 Hz. So this frequency could boom or null out. Right in the lower register of the classical guitar.
An interesting thing to do is to put a quality speaker in your bathroom and feed a sine wave sweep from 40 to 10KHz etc. Put an omni directional quality mic in there and have a look at the level variations. You might be pretty surprised. Funny things will happen at the three room dimension frequencies for sure.
Recording in a more dead environment and up a little closer and using a very nice sounding convolution reverb with a nice small live room to my ears sounds a lot better.