What is it against dryers?

Oh, I do clean the rubber seal bit... that seemed obvious to me!  But given the lack of bad odour, I never thought about the rest of it.  On the back of this thread, I saw online that a solution of baking soda and vinegar run through a wash cycle will clean it, so I might do that just to be on the safe side. 

Baking soda and vinegar does works wonders, too. Also, soda crystals.

When we moved in, there was blackish brown mold in the tray area and the seal (rented apartment so it had been used before), and it comes back when not cleaned, causing the smell 

make sure when buying get a vented dryer / condenser dryers take forever to dry and cost for drying is $$$$$ or £££££ ..