Sulekha.com is just a collection of information and answer to whether it is reliable or not is not really simple. As far as advertisers are concerned, there are complaints against sulekha dot com that they do not have a refund policy and they just swallow money without providing customer support and yes they also make false promises, do not believe the author just google around sulekha dot com complaints and you would say for yourself that sulekha.com is not a reliable website.
Sulekha Classifieds is also a place where people post free or paid advertisements, now in this case sulekha just provides a platform to post free or paid classifieds and people are themselves responsible for everything. I guess Sulekha.com cannot be blamed for anything that goes wrong. Hence reliability of sulekha.com is in the case of sulekha classifieds is i guess limited to technical availability of the website and not for the content posted on sulekha classifieds. Similar explanation would apply for advertisements posted on sulekha classifieds, i guess sulekha staff would do some basic communication with the advertiser, take the money or provide the advertisement and that’s it, if you communicate with the advertiser in any way, you are fully responsible for it.