Patches on bathroom floors

[jo]

Wonder if anyone have those patches on the bathroom floors.. my colleagues used to tell me to overlay the tiles when I move in cause these are inferior tiles.... did not listen to them  so now have to suffer patchy floors..

Does anyone have any methods to remove them?

[Angel]

is it the mould we are talking about in the other thread?

[sakori]

huh..gt such thing ars..didnt noe

[Chilliqueen]

Hi, Jo
Wat's the color of yr floor tiles?
I had my bathroom tiles overlayed n until late last year, i noticed the grey patches starts appearing at the 'shower zone' .. n unluckily my tiles r beigh color..so the patches r quite obvious..
can't figure out wat causes it and i tried all methods to remove it but to no avail...I even pour bleach on the patches, soak for few hrs..then scrub..tat only lightens the patches and the greying gets darker again after some time...Sigh, regret liao..! shld have overlay wif black tiles instead... 
BTW, hav u try any removal methods yet?