Just a quick glance at schnauzers and I'm seeing these things that could be an issue. 1. Their size can range from quite small to very much full-size. Think along the same range as poodles-- from manageable to those gawdawful massive abominations. 2. They can be yappy. Think along the same lines as women-- they can be trained, some are even less-prone, but there's definitely potential for difficulty. 3. They need to be socialized or can become territorial towards other people/pets. Maybe the two of youse can consider that something to bond over. 4. They need to be kept groomed. Haircuts. Baths. Spa days.
How young is the one you have been offered? If it's a few months old and nobody has been working with it on some of these issues, as well as training it, then there's potentially an uphill battle. Younger is definitely a plus.
Consider costs for shots, toys, bedding, leash, collar, 'crate' so you can keep it from destroying stuff if/when you aren't there, food, treats. Initial costs can be higher than expected.
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