Certain number combinations are always a plus. For example; keyword411.com or 123abc.com. Anything that has memorability is going to work whether it contains numbers or letters.
Heh! Back in the 90s, a number domain was the in thing. All the directories used alpha listings and the numbered domains were usually at the top. From a visibility and indexing perspective, this was king at the time. I played the numbers game for about a year and moved towards a branding model after seeing what I was getting into. ;)
No, domains that start with numbers are not bad for anything, including SEO. As mentioned above though, you have to be careful with the combinations so as not to create the 2, two, to, scenario. The last thing you want to have to do is spell out your domain "all the time". I have a client or two like that due to branding issues. Thankfully we have the typo versions 301'ing to the primary.