DON'T BUY A DOG IF YOU ARE 
FASTIDIOUS ABOUT YOUR HOME.

Most long haired breeds are a highly efficient form of transportation for dirt into your home.  Once in your home, the job continues by depositing same on your floors and rugs and possibly also on your furniture and clothes. Even short coated breeds are not fastidious.  Dogs are dogs, and as a rule they prefer to be dirty and smelly.  Think of it as a dog status symbol.  

Some breeds are seasonal shedders, and in spring some can easily fill a trash bag with balls of hair from a grooming session, or clog a vacuum cleaner if left to shed in the house. 

Then there are the "dumpster divers".  There isn't a dog alive that won't take the opportunity to dig chicken bones out of an unsecured trash can.  Of course, the dog's discriminating palette will mean cans and paper towels that shared said trash can with the bones will be scattered willy-nilly across your kitchen floor.  

This isn't meant to imply that you must be a slob to live happily with a dog (especially a long coated variety), but you do have to have the attitude that your dog's company means more to you than maintaining perfect cleanliness. You will frequently find that being comfortable with a less than immaculate house is desired trait among dog owners.

All dogs, like all children, create a greater or lesser degree of household mess and chaos. The Basenji is perhaps the cleanest, due to its cat-like habits; but cats are cleaner yet, and goldfish hardly ever mess up the house.

DON'T BUY A NEWFOUNDLAND, MASTIFF, SAINT BERNARD, GREAT PYRENEES, ROTTWEILER, BERNESE MOUNTAIN DOG OR OTHER LARGE BREED IF YOU FIND DROOL TOTALLY REPELLANT

Most "wet mouthed" breed owners begin with some degree of distaste for drool, but as this is an integral part of living with these breeds, this dislike usually progresses to some level of nonchalance. 

A sure sign of a Newfoundland, St Bernard or Mastiff addict is that not only do they not understand other people's squeamishness for this substance, they spend many hours trying to come up with useful purposes for the gallons of drool that can be produced on a regular basis. 

Some say that the world record "drool toss" from an adult Newfoundland is over 20 feet however, Saint Bernard lovers are sure this record was set by their breed.  In either case, this makes your walls and ceilings well within reach of even an average drooler of the large, loose flewed variety. 

Large, mastiff type dogs drool because of their jaw and mouth structure. PERIOD.   Run quickly from the breeder of the above mentioned breeds who claims his/her pups are "dry-mouthed".  

If you cannot get used to the idea of drool in your house, then try one of the many breeds of dogs that do not drool. Although there is the occasional cat who drools, the quantity is not remotely comparable to a dog, and hamsters don't drool at all.

DON'T BUY A DOG IF YOU DISLIKE
DOING REGULAR GROOMING. 

It's not only the thick shaggy Newfoundland coat that demands regular grooming, but all long haired and most short coated breeds require at least a weekly brushing.  Grooming is necessary not merely to look tolerably nice, but also to preserve the health of skin underneath and to detect and remove foxtails, ticks, and other dangerous invaders. 

For "pet" grooming of long coated varieties, you should expect to spend 10-15 minutes a day (e.g. while listening to music or watching television) on alternate days or half an hour twice a week. Short coated breeds can get by with a quick once over weekly.  Of course any time your dog gets into cockleburs, filigree, or other coat-adhering vegetation, you are likely to be in for an hour or more of remedial work. 

During the summer months, you must inspect the feet and other vulnerable areas on your dog daily.  "Pet" grooming does not require a great deal of skill, but does require time and regularity. "Show" grooming requires a great deal of skill and considerably more time and effort or expensive professional grooming.

Almost every long haired dog that is rescued out of a pound or shelter shows the effects of many months of lack of grooming, resulting in massive matting and horrendous filthiness, sometimes with urine and feces cemented into the rear portions of the coat. It appears that unwillingness to keep up with coat care is a primary cause of abandonment of long haired breeds.  Make sure you're up to the task before adopting a high maintenance dog.