Not all search spiders are mallicious, in fact, most won't touch anything but text on your site. If you don't want spiders crawling your member data, you should disable the ability for guests to view profiles.
As for "is this normal" yes, anything on the internet that is public to all guests should eventually get crawled by a spider; it's completely normal, they crawl data, it's what they're designed to do... even when you don't tell them to (as they come in from links from other pages or other sites).
There are ways to "blackhole" bad spiders, I made a post on this like a year ago, it's here somewhere... I never really looked into integrating it with the ubb, but it'd at least build a list of bad spiders for you to block manually.
Good spiders: crawl your content, based on criteria you specify (read up on robots.txt)
Bad Spiders: crawl your content, most take what they want (and completely ignore your robots.txt)
Mallitious Spiders: grab email addresses and user data (hence why there is the ability to block guests from accessing profiles).
