Thank God someone has shown a little restraint with the last crop of reality shows: Blue-chip advertisers have largely avoided buying time in cheesefests such as ABC's ''Are You Hot?'' -- leaving the nets scrounging for spots from the likes of Bowflex, Hair Club, and the E! channel, peddler of ''The Anna Nicole Show.'' ''Hot,'' which ranks third in its time slot and averages only 10.1 million viewers, gets upwards of $75,000 per 30-second commercial -- if the space sells at all. In fact, almost half the ''ads'' that ran during the Feb. 27 ''Hot'' were promos for ABC series and other Disney-owned ventures. The good news for ABC is that when a reality show pulls in decent numbers, advertisers dismount their high horses. Big companies flocked to ''The Bachelorette,'' for example, which was able to command a ''Friends''-like rate of $400,000 for some spots. ''For many buyers, big ratings make a lot of concerns over content go away,'' says one rival network head. ''But 'Hot' is pure and simple T&A. What redeeming value is there in that?'' Apparently not much -- unless you're hawking PastaPro.