Here’s a handy tool I just came across: http://tools.seobook.com/spelling/keywords-typos.cgi
What it does: it creates a list with the most common typos for your (negative) keywords.
Why you’d care:
1. Negative keywords don’t do close variants; you’ll have to add each and every frequent typo to prevent your ad from showing.
2. To prevent PMax from hijacking your brand traffic, adding typos to your brand campaign and/or PMax negative keyword lists is a must.
PRO TIP: Create a script that automatically adds close variant search terms as new keywords to your branded campaign. This will prevent PMax from taking priority for these searches. In theory, at least.
– Nils