Why would a bathroom emit an odor if pipes aren't clogged?
Sounds like you are smelling sewer gases. Two common ways those will come up drain lines are from a dry trap (make sure water has run in each drain within the past several months) or a failing wax seal under the toilet (you may notice water damage under the toilet when this happens, but not always). The other issue could be a blocked vent line which would result in gurgling in a drain when you use the plumbing elsewhere.