I've tried manually cutting out the 'lip' sounds, but it's quite a task to do that without altering the words. The recording is gated (do you often gate voice-overs?), but it doesn't solve the problem: a majority of those sound occur during the speech itself, unlike breaths.
1) id never gate a recording ever. Infact Id NEVER process a recording ever no compression, gate reverb eq. That is something that is exclusive to the final mixdown, where it can always be un picked and more importantly processed with all of the final mix elements in mind so its done in situ!. I dont understand the need to record with an effect. Like a cup of tea, once youve put sugar in you cant extract it. But you can always add a little sugar just before drinking.
2) If the talent makes any additional noises other than whats on the script, they get to go and do it again. Thats what im spraying money at them for.
3) If its already been done like that by someone else, and i couldnt clean it up correctly without clipping the words, id reject it as not up to spec and await the correct version.
40 if it couldnt be re done (ie the VO has died) then id do my best and make sure the client understands that the faults were not of my making.