Some are "rental community parks" while others are Condo conversions, (formerly a rental community turned to private residential condo ownership) or possibly even a "Planned Unit Development" aka a "PUD" which was a planned residential development that chose to utilize "Factory Built" in lieu of "Site Built" homes.
In any event, as in any other neighborhood, if the community is will maintained it shouldn't impact your value. If, however, it's blighted with junk cars scattered about and lot's of run down and/or abandoned homes I'd be looking for another home.
Being next to a mobile home park will not necessarily depress your resale vale, unless the home has a view of it, and the view is unpleasant. Many of the mobile home communities in Sunnyvale are being sold off and turned into town homes so it is very likely that even if there is a mobile home there now, when you go to sell it may not be there.
If you don't have an agent, get one right here, just look over the profiles of a few of us and pick a few to interview and go with the agent you feel will represent you best.
Feel fee to contact me with any questions.
At your service,