When we purchased our town-home here on the peninsula, we had a small dachshund mix and never thought twice about asking about pet restrictions. She was a small breed and we saw some other people with dogs during the time we previewed the home, so we just assumed it was OK.
It's not a good idea to assume your pet will be accepted, especially in a condo building. These condos often have strict guidelines to having pets. Even if the CC&R's report that you may have three pets, it often means three different types of species. For example: One small dog, a pet bird, and a cat.
Pet weight restrictions are most prevalent in a condo situation. Last summer I found the perfect condo for a prospective buyer. She has two sweet Italian Greyhounds that weigh very little, however the HOA documents clearly restricted homeowners to only one dog. She luckily found a condo shortly afterwards that had a two dog limit.
The best advice I can give you is to investigate the CC&R's pet policy before looking at a condo. It's also a good idea to see if the surrounding neighborhood has parks and walking trails that are pet friendly.
Last, but not least.....be a responsible pet owner......while walking your most precious 4 legged family member, don't forget to pick up after.........