In your experience, do most players "fold" when someone who seldom plays enters the pot? Does this mean that it is a good idea to play in some borderline (presumably break even) situations, just to weaken perceptions of one's being tight? And how, if at all, does this vary from low to high limit games?
What you're talking about is called Table Image.
Table image is important because it represents what other players think they know about you and how you play. If you play very tight (very few hands, only very good cards), and players see this, they're only going to stay in the pot with you, if they also have very good cards (in which case you should be a little worried).
It's not strictly true that you must LOSE hands (VPIP, or hands you voluntarily put into the pot), but you do need to play such that your opponents don't know what kind of cards you might have. This may mean bluffing 10% of the time, or it could be more sophisticated, like always playing in position (when you're one of the last to bet), since then they won't know if you have good cards, or are just playing position.
In general though, if ALL you do is only bet when you have a tier 1 hand, then yes, people are just going to fold.
Like Neal says this is called Table Image. If you just draw crappy cards for a while and realize people probably see you as tight then that is great! No matter what your table image is you can use it to your advantage if you know about it. Say they think you're really tight, then you'll have an easy time stealing pots with bad cards. Or if they think you're quite loose you probably will get more action on your great hands.
Don't bother thinking about if you need to give action to not seem too tight. Instead use your table image to your advantage and scare them out of pots you want to win fast!
It really depends on your opponents.
If you're playing a typical low-limit online table, for example, most of your opponents are probably multi-tabling and not paying much attention to what you're doing; unless they're using stat-tracking software, it's unlikely they have any idea how often you've been playing.
Chances are, if you're stealing the blinds as often as you should, people will call