Sherry Fitzgerald, the prominent estate agents, has been prosecuted 106 times since the introduction of the 1997 Litter Pollution Act.
The company was advertising illegally by putting up "for sale" signs in public places in Dublin, rather than solely on private grounds, according to Dublin Corporation. Lowe & Associates, another estate agency, fell foul of the litter Act six times for similar reasons: putting pointer signs at the end of a road to indicate a house for sale.
The 1997 Act also makes it illegal to put flyers on windscreens and to use flyers to advertise.
It is also against the law for anyone to put out rubbish on a non-bin collection day.
Businesses can also be prosecuted if the paths in front of their shops are not kept clean. Just last month a shop in Henry Street was fined £500 for not keeping up appearances.
The crackdown is part of moves by Dublin Corporation to rid Dublin of its "dirty" image. In the first seven months of this year, some 6,000 on-the-spot £25 fines (with 21 days to pay) were issued, compared to 4,000 for all of last year.
And practically every week of the legal calendar offending businesses and individuals who have dropped litter on the streets have been prosecuted in the District Court for non-payment of fines - 543 prosecutions so far this year, compared to 343 in the first six months of last year.
However, in the past six months there have been no prosecutions for illegal advertising of sale signs. According to Mr Kevin O'Sullivan, Dublin Corporation's anti-litter officer, that problem has cleared up.
Mr Simon Ensor, a Sherry Fitzgerald director, confirmed this. At the time the fines were enforced he believed one or two of the bigger agencies were being made examples of. "It was an unlevel playing pitch. There might be three signs up and we'd be summonsed."
Sherry Fitzgerald, he said, kept putting up the signs until everyone was treated equally and everyone was fined. Now estate agents were happy that nobody had any such signs up. "The institute [Irish Auctioneers and Valuers Institute] is very vigilant and anybody putting up signs is reported now to the corporation."
However, this kind of activity is just one part of a campaign to increase anti-litter awareness. Mr O'Sullivan points out that "we've been bringing people to court since the 1980s under the 1982 Litter Act, although not in the same organised way as now".
In the last two years, the number of litter wardens has increased from two to 20, along with a corresponding increase in on-street cleaning vans which are moving into all areas of Dublin. "Dublin city goes out to Ballymun and Santry and Terenure on the other side," said Mr O'Sullivan. "We're not just staying in the city centre."