Is it bad for health to smell farts? is it toxic to smell and/or breath in your own farts or someone else's farts? i read that farts were toxic gas...

No: The sulfides in fart gas are toxic only if you were breathing them invert high concentrations, like pretty much everything else. You can actually inhale the gas up close, as may happen in sexual situations, without fear.

No: There are gases that could be toxic in farts but not at the concentration that you would just smell them as the gas rapidly dissipates. In order for you to have toxic effects, you would have to trap the gas in a bag and hold it over your mouth. You are more likely to suffocate from lack of oxygen than dye of the gas.