Brokers and agents misuse apartments

Q: Was recently hunting for apartment @ Tambaram , Jain Abhishek , Pace Adarsha for buy/rent. Bumped into someone camouflaging as agents claim control of apartments getting vacant , trying to monopolize rent, lease and sell . Later found these blokes deliver paper, milk etc having tie-up with brokers acting as mediators . Very surprising to see them having the keys of multiple houses and allowing strangers inside apartments at will. As these apartments are mostly owned by NRI, they simply misuse these apartments, and even go to the extent of sub-letting it for few weeks to a month till someone genuine approach for a longer stay. I myself have been through these issues when I was abroad, where my house was used as a club by some loafers in that area and hence this post is to basically to warn the owners keep the custody of the house with some trusted people, friends or relatives.