monoxide with smell like rotten egg

"Characteristic" smell in some gasoline catalysts, I have smelled many times already, and that smell does not always occur in the same car .. (I have wondered more than once because of this) if the temperature and humidity influences (especially in winter when starting) and then disappears ... although it is true that in other cars it does not smell of anything ... Some marks are more prone (vag group of the vag from the mid -90s. Perfect and there was no failure ... but as "Fiat 147" says; It should not be normal and of course "because" it has to have and it would be good to know what it is due. Greetings!!

hahaha the normal word, I laugh at that it is not extraordinary, they will only be caused by the western of condensed water, in contact with the reagents of Catalan.

Yes, that I think it should be, I already say that I have always noticed it in winter (with humidity) and then in summer, not ... but there are cars in which this is not appreciated, it will be the type of metals that the catalyst carries are different according to the motor, brand or that it meets another new regulation of emissions ... (here we talk about a car manufactured in China ...) It is a curiosity for me, nothing more. greetings!!