I've recently been told that the word "clothes" is actually pronounced as "close", because an American friend heard me saying it with a voiced TH sound.
The thing is I usually can't hear the difference in sounds between TH and D, F or T, so I just rely on knowing where to place my tongue in order to pronounce TH sounds and do this every time a word is spelled with a TH.
Are there other common words like "clothes" that are spelled with a TH but not actually pronounced with a standard voiced/voiceless TH? Or is this just a very rare exception?