Accommodation in Colombia: scams you should look out for

Hi Bhavna.

Thanks for sharing this however, for me it's my second home. You should be versed with the Spanish language before visiting as recommendation. For me I'm MPhil in Spanish language, literature and cultural studies and that's how it's helps me knowing their roots better than most of them with all the aspects. Having said this I'm NOT AT ALL having immunity against all the hickups though.
Feel free to connect me for any query ****
Regards,
Ather A

Use AirBNB and negotiate the price down

What are the most common scams in Colombia?
Renting from a current renter who turns around and sublets to you without any lease papers,
Do not rent from anyone with out a lease!

What are the red flags to look out for when scanning through
A lot of the places will already be rented,  be prepared to not hear back from your inquiry.

Is there a list of registered or accredited landlords or real estate agencies in Colombia?
Yes. Medellin Guru has detailed information on his site about renting and all things regarding  moving to Colombia.

What authorities should be sought should one come across an accommodation?
Good question.

If you do not speak Spanish well hire an advocate to help you with renting, visa, banking, and health care. It will make it a lot easier for you.  There are some highly rated advocates/ relocation assistants on Facebook , Medellin Expat page.