Vclaw
3
First you should start by reading the import guidelines: http://wiki.openstreetmap.org/wiki/Import/Guidelines
Specifically the section for making sure the data license is OK. Most company websites are copyright, so you shouldn’t be copying from them to add to OSM, unless you have explicit permission.
Also discussing it with the community first.
If you do have fuzzy data (with a suitable license), then it may not be best to import it directly into OSM. Instead, you could use it as sort of checklist.
See for example this UK Bike shop locator tool: http://shaunmcdonald.dev.openstreetmap.org/bike-shop-locator/ You can mark whether or not a shop is mapped in OSM, if its not mapped, you can go out and survey it and map it in the usual way.