After taking shower a smell comes from the drain. I have use several bottles of liquid plumber. On all the drains in the bathroom. The smell went away after each time I used the liquid plumber. But after using the shower it comes right back. I live a trailer that is 15 years old. I checked the trap to see if there is a leak and there isn't. I need to know what to do. Can someone please help me with this.

Most bad odors in bathroom drains come from rotting hair mixed with grease from the soap. Try this. Remove the two screws holding the strainer. (TIP; put the screws in the soap dish before they get lost down the drain.) Shine a light down there and with a bent coathanger fish out any hair that may be hiding down there. Then pour a 1/2 gal. of bleach down into the trap and let it set over night. Next morning flush the mess down with 2 large pans of boiling water, (this is important). The bleach will dissolve the hair and make it slippery and the boiling water will melt the grease and get the mess out of your drain. Smell better now? Cheers TOM