Having river both in front and at the back of house. - Danger of water weakening the foundation

Having toilet in the middle of the house - In Feng Shui, the middle of the house is Five Yellow or Five Ghosts.
Any unclean materials here will energize the Five Ghosts causing misfortune for the occupants.

Main door in line with back door - Chi that flows in from the front door will flow out of the back door directly. Money comes, money goes.

Main door in line with bedroom door - Unhappy relationship, insomnia, extra marital affairs.

Font door in line with toilet door - Bad for health of the occupants.

Main door facing T-junction - Very bad fengshui, cause sicknesses or death of occupants.

Cul De Sac, house situated at dead end road - Chi, like blood in our body need to flow, any trapped chi will cause stagnantion leading to negative influence on the brain. Mental illnesses, depression, confusion and aggression.

House with insufficient sunlight - A house that are not bright can easily attract evil spirits.

Main doors - Evil-looking or old trees directly outside main door can cause the house's magnetic field to become too Yin. Health problems

Large house with few occupants - Not enough Yang energies and leading to health problems to occupants.

House with missing sectors - Each sector of a house governs a specific member of the family.
Example: a missing East sector will affect the elder son in the family.

3, 4, 8 Rooms - In Fengshui theory, the total number of rooms(including toilet) in the house should not be 3, 4, or 8.

Having toilet near to kitchen - Traditionally, kitchen is Fire and toilet is Water element. Having the two elements clashing will cause serious stomach and digestive problems

Bedroom situated above a balcony - The movements of people and chi below the bedroom cause too much magnetic disturbances to the bedroom. A resting person needs a stable and peaceful surrounding.

Balcony directly in line with kitchen door - Extra marital affairs(especially the wife), children will not like staying at home.

Mirrors - Avoid having big mirrors in the house, they disrupt the balance and flow of healthy Chi.