it's not good to hear that you get spam on your new addresses. You didn't describe this a lot though -- perhaps the spam is simply sent to a gazillion random addresses and you simply got hit by chance. Did you turn on the spam filter?
I don't think that the spam is actually sent to your mailbox names, but the headers can be confusing about this, especially if the sender "cheats" and sends out incomplete headers because then the DreamHost mail server has to fill in some values and that makes it look worse than it really is. Also, the numbers aren't really sequential; if you create six in a row then you'll see that the numbers are very different from each other (at least when I did this).
If you're new here, then you can take advantage of the 91-day money-back guarantee. You could also wait until you're at "day 89" before leaving -- so you get more time to try out this host.
Best of luck,
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