IME: Grout does this. It's a maintenance issue; clean it aggressively on a regular basis to keep it from getting out of hand.
It's possible someone used Latex based grout, which molds up much faster and blacker than other cement or epoxy grout. Stay away from the ready mixed grouts at the big box stores: you can clean and seal this stuff, but all you're doing is pushing the recurance back a bit further.
If you really want to get throw money at the problem, you want to look for a tile specialist: lot of folks specialize in doing tile work: you can find them advertising in tile stores or here:
no subject
It's possible someone used Latex based grout, which molds up much faster and blacker than other cement or epoxy grout. Stay away from the ready mixed grouts at the big box stores: you can clean and seal this stuff, but all you're doing is pushing the recurance back a bit further.
If you really want to get throw money at the problem, you want to look for a tile specialist: lot of folks specialize in doing tile work: you can find them advertising in tile stores or here:
http://maps.google.com/maps?hl=en&source=hp&oq=&um=1&ie=UTF-8&q=tile+setters+jersey+city&fb=1&gl=us&hq=tile+setters&hnear=jersey+city&view=text&ei=GpeNS6-QG8-XtgfXoqDwCA&sa=X&oi=local_group&ct=more-results&resnum=1&ved=0CB0QtQMwAA
Or you could try to get handy: cut the grout out and redo it with quality grout and seal well (if you're not going for epoxy).