As Long as You Have a Good Deliverability Rating, You're Safe
Bounces from guessed emails are not significant to the reputation you have with your mailing service. This is because, even when an email is guessed, we only give it to you if we're at least 60% confident it won't bounce. Confidence level is extrapolated by our manual verification team, and and can be found by hovering over the mail icon for a given contact.
Note: Guessed emails should work at least 60% of the time, but it's actually higher in practice. Emails are occasionally marked as guessed because the contact's email server does not allow crawlers or verification.
With all of that said, if you do have a high bounce rate, do not send guessed emails through your sequences until you repair your reputation with your mailing service. Talk to your CSM about this if you have any questions. We're happy to help!